AutoSegment Triangulation Cluster Tool at GEDmatch

Today, I’m reviewing the exciting new AutoSegment Triangulation Cluster Tool at GEDmatch. I love it because this automated tool can be as easy or complex as you want.

It’s easy because you just select your options, run it, and presto, you receive all kinds of useful results. It’s only complex if you want to understand the details of what’s really happening beneath the hood, or you have a complex problem to unravel. The great news is that this one tool does both.

I’ve taken a deep dive with this article so that you can use AutoSegment either way.

Evert-Jan “EJ” Blom, creator of Genetic Affairs has partnered with GEDmatch to provide AutoSegment for GEDmatch users. He has also taken the time to be sure I’ve presented things correctly in this article. Thanks, EJ!

My recommendation is to read this article by itself first to understand the possibilities and think about how you can utilize these results. Then, at GEDmatch, select the AutoSegment Report option and see what treasures await!

Genetic Affairs

Genetic Affairs offers a wide variety of clustering tools that help genealogists break down their brick walls by showing us, visually, how our matches match us and each other. I’ve written several articles about Genetic Affairs’ tools and how to use them, here.

Every DNA segment that we have originated someplace. First, from one of our parents, then from one of our 4 grandparents, and so forth, on up our tree. The further back in time we go, the smaller the segments from those more distant ancestors become, until we have none for a specific ancestor, or at least none over the matching threshold.

The keyword in that sentence is segment, because we can assign or attribute DNA segments to ancestors. When we find that we match someone else on that same segment inherited from the same parent, assuming the match is identical by descent and not identical by chance, we then know that somehow, we shared a common ancestor. Either an ancestor we’ve already identified, or one that remains a mystery.

Those segments can and will reveal ancestors and tell us how we are related to our matches.

That’s the good news. The bad news is that not every vendor provides segment information. For example, 23andMe, FamilyTreeDNA, and MyHeritage all do, but Ancestry does not.

For Ancestry testers, and people wishing to share segment information with Ancestry testers, all is not lost.

Everyone can download a copy of their raw DNA data file and upload those files to vendors who accept uploads, including FamilyTreeDNA, MyHeritage, and of course GEDmatch.

GEDmatch

GEDmatch does not offer DNA testing services, specializing instead in being the common matching denominator and providing advanced tools. GEDmatch recently received a facelift. If you don’t recognize the image above, you probably haven’t signed in to GEDmatch recently, so take a look. The AutoSegment tool is only available on the new version, not the Classic version.

Ancestry customers, as well as people testing elsewhere, can download their DNA files from the testing vendor and upload the files to GEDmatch, availing themselves of both the free and Tier 1 subscription tools.

I’ve written easy step-by-step download/upload instructions for each vendor, here.

At GEDmatch, matching plus a dozen tools are free, but the Tier 1 plan for $10 per month provides users with another 14 advanced tools, including AutoSegment.

To get started, click on the AutoSegment option.

AutoSegment at GEDmatch

You’ll see the GEDmatch AutoSegment selection menu.

You can easily run as many AutoSegment reports as you want, so I suggest starting with the default values to get the lay of the land. Then experiment with different options.

At GEDmatch, AutoSegment utilizes your top 3000 matches. What a huge, HUGE timesaver.

Just a couple of notes about options.

  • My go-to number of SNPs is 500 (or larger,) and I’m always somewhat wary of matches below that level because there is an increased likelihood of identical by chance segments when the required number of segment matching locations is smaller.
  • GEDmatch has to equalize DNA files produced by different vendors, including no-calls where certain areas don’t read. Therefore, there are blank spaces in some files where there is data in other vendors’ files. The “Prevent Hard Breaks” option allows GEDmatch to “heal” those files by allowing longer stretches of “missing” DNA to be considered a match if the DNA on both sides of that blank space matches.
  • “Remove Segments in Known Pile-Up Regions” is an option that instructs GEDmatch NOT to show segments in parts of the human genome that are known to have pile-up regions. I generally don’t select this option, because I want to see those matches and determine for myself if they are valid. We’ll look at a few comparative examples in the Pileup section of this article.

Fortunately, you can experiment with each of these settings one by one to see how they affect your matching. Even if you don’t normally subscribe to GEDmatch, you can subscribe for only one month to experiment with this and other Tier 1 tools.

Your AutoSegment results will be delivered via a download link.

Save and Extract

All Genetic Affairs cluster files are delivered in a zipped file.

You MUST DO TWO THINGS, or these files won’t work correctly.

  1. Save the zip file to your computer.
  2. Extract the files from the zip file. If you’re on a PC, right-click on the zip file and EXTRACT ALL. This extracts the files from the zipped file to be used individually.

If you click on a feature and receive an error message, it’s probably because you either didn’t save the file to your computer or didn’t extract the files.

The file name is very long, so if you try to add the file to a folder that is also buried a few levels deep on your system, you may encounter problems when extracting your file. Putting the file on your desktop so you can access it easily while working is a good idea.

Now, let’s get to the good stuff.

Your AutoSegment Cluster File

Click on the largest HTML file in the list of your extracted files. The HTML file uses the files in the clusters and matches folders, so you don’t need to open those individually.

It’s fun to watch your clusters fly into place. I love this part.

If your file is too large and your system is experiencing difficulty or your browser locks, just click on the smaller AutoSegment HTML file, at the bottom of the list, which is the same information minus the pretty cluster.

Word to the wise – don’t get excited and skip over the three explanatory sections just below your cluster. Yes, I did that and had to go back and read to make sense of what I was seeing.

At the bottom of this explanatory section is a report about Pileup Regions that I’ll discuss at the end of this article.

Excel

As a third viewing option, you can also open the AutoSegment Excel file to view the results in an excel grid.

You’ll notice a second sheet at the bottom of this spreadsheet page that says AutoSegment-segment-clusters. If you click on that tab, you’ll see that your clusters are arranged in chromosome and cluster order, in the same format as long-time genetic genealogist Jim Bartlett uses in his very helpful blog, segment-ology.

You’ll probably see a message at the top of the spreadsheet asking if you want to enable editing. In order for the start and end locations to calculate, you must enable editing. If the start and end locations are zeroes, look for the editing question.

Notice that the colors on this sheet are coordinated with the clusters on the first sheet.

EJ uses yellow rows as cluster dividers. The “Seg” column in the yellow row indicates the number of people in this cluster group, meaning before the next yellow divider row. “Chr” is the chromosome. “Segment TG” is the triangulation group number and “Side” is Jim Bartlett’s segment tracking calculation number.

Of course, the Centimorgans column is the cM size, and the number of matching SNPs is provided.

You can read about how Jim Bartlett tracks his segment clusters, here, which includes discussions of the columns and how they are used.

Looking at each person in the cluster groups by chromosome, *WS matches me and *Cou, the other person in the cluster beginning and ending at the start and end location on chromosome 1. In the match row (as compared with the yellow dividing row,) Column F, “Seg,” tells you the number of segments where *WA matches me, the tester.

A “*” before the match name at GEDmatch means a pseudonym or alias is being used.

In order to be included in the AutoSegment report, a match must triangulate with you and at least one other person on (at least) one of those segments. However, in the individual match reports, shown below, all matching segments are provided – including ones NOT in segment clusters.

Individual DNA Matches

In the HTML file, click on *WA.

You’ll see the three segments where *WA matches you, or me in this case. *WA triangulates with you and at least one other person on at least one of these segments or *WA would not be included in the GEDmatch AutoSegment report.

However, *WA may only triangulate on one segment and simply match you on the other two – or *WA may triangulate on more than one segment. You’ll have to look at the other sections of this report to make that determination.

Also, remember that this report only includes your top 3000 matches.

AutoSegment

All Genetic Affairs tools begin with an AutoCluster which is a grouping of people who all match you and some of whom match each other in each colored cluster.

AutoSegment at GEDmatch begins with an AutoCluster as well, but with one VERY IMPORTANT difference.

AutoSegment clusters at GEDmatch represent triangulation of three people, you and two other people, in AT LEAST ONE LOCATION. Please note that you and they may also match in other locations where three people don’t triangulate.

By matching versus triangulation, I’m referring to the little individual cells which show the intersection of two of your matches to each other.

Regular AutoCluster reports, meaning NOT AutoSegment clusters at GEDmatch, include overlapping segment matches between people, even if they aren’t on the same chromosome and/or don’t overlap entirely. A colored cell in AutoSegment at GEDmatch means triangulation, while a colored cell in other types of AutoCluser reports means match, but not necessarily triangulation.

Match information certainly IS useful genealogically, but those two matching people in that cell:

  • Could be matching on unrelated chromosomes.
  • Could be matching due to different ancestors.
  • Could be matching each other due to an ancestor you don’t have.
  • May or may not triangulate.

Two people who have a colored cell intersection in an AutoSegment Cluster at GEDmatch are different because these cells don’t represent JUST a match, they represent a TRIANGULATED match.

Triangulation tightens up these matches by assuring that all three people, you and the two other people in that cell, match each other on a sufficient overlapping segment (10 cM in this case) on the same chromosome which increases the probability that you do in fact share a common ancestor.

I wrote about the concept of triangulation in my article about triangulation at GEDmatch, but AutoSegment offers a HUGE shortcut where much of the work is done for you. If you’re not familiar with triangulation, it’s still a good idea to read that article, along with A Triangulation Checklist Born From the Question; “Why NOT use Close Relatives for Triangulation?”

Let’s take a look at my AutoSegment report from GEDmatch.

AutoSegment Clusters at GEDmatch

A total of 195 matches are clustered into a total of 32 colored clusters. I’m only showing a portion of the clusters, above.

I’ve blurred the names of my matches in my AutoSegment AutoCluster, of course, but each cell represents the intersection of two people who both match and triangulate with me and each other. If the two people match and triangulate with each other and others in the same cluster, they are colored the same as their cluster matches.

For example, all 18 of the people in the orange cluster match me and each other on one (or more) chromosome segments. They all triangulate with me and at least one other person, or they would not appear in a colored cell in this report. They triangulate with me and every other person with whom they have a colored cell.

If you mouse over a colored cell, you can see the identity of those two people at that intersection and who else they match in common. Please note that me plus the two people in any cell do triangulate. However, me plus two people in a different cell in the same cluster may triangulate on a different segment. Everyone matches in an intricate grid, but different segments on different chromosomes may be involved.

You can see in this example that my cousin, Deb matches Laurene and both Deb and Laurene match these other people on a significant amount of DNA in that same cluster.

What happens when people match others within a cluster, but also match people in other colored clusters too?

Multiple Cluster Matches = Grey Cells

The grey cells indicate people who match in multiple clusters, showing the match intersection outside their major or “home” cluster. When you see a grey cell, think “AND.” That person matches everyone in the colored cell to the left of that grey cell, AND anyone in a colored cell below grey cells too. Any of your matches could match you and any number of other people in other cells/clusters as well. It’s your lucky day!

Deb’s matches are all shown in row 4. She and I both match all of the orange cluster people as well as several others in other clusters, indicated by grey cells.

I’m showing Deb’s grey cell that indicates that she also matches people in cluster #5, the large brown cluster. When I mouse over that grey cell, it shows that Deb (orange cluster) and Daniel (brown cluster) both match a significant number of people in both clusters. That means these clusters are somehow connected.

Looking at the bigger picture, without mousing over any particular cell, you can see that a nontrivial number of people match between the first several clusters. Each of these people match strongly within their primary-colored cluster, but also match in at least one additional cluster. Some people will match people in multiple clusters, which is a HUGE benefit when trying to identify the source ancestor of a specific segment.

Let’s look at a few examples. Remember, all of these people match you, so the grid shows how they also match with each other.

#1 – In the orange cluster, the top 5 rows, meaning the first 5 people on the left side list match other orange cluster members, but they ALSO match people in the brown cluster, below. A grey cell is placed in the column of the person they also match in the brown cluster.

#2 – The two grey cells bracketed in the second example match someone in the small red cluster above, but one person also matches someone in the small purple cluster and the other person matches someone in the brown cluster.

#3 – The third example shows one person who matches a number of people in the brown cluster in addition to every person in the magenta cluster below.

#4 – This long, bracketed group shows several people who match everyone in the orange cluster, some of whom also match people in the green cluster, the red cluster, the brown cluster, and the magenta cluster. Clearly, these clusters are somehow related to each other.

Always look at the two names involved in an individual cell and work from there.

The goal, of course, is to identify and associate these clusters with ancestors, or more specifically, ancestral couples, pushing back in time, as we identify the common ancestors of individuals in the cluster.

For example, the largest orange cluster represents my paternal grandparents. The smaller clusters that have shared members with the large orange cluster represent ancestors in that lineage.

Identifying the MRCA, or most recent common ancestor with our matches in any cluster tells us where those common segments of DNA originated.

Chromosome Segments from Clusters

As you scroll down below your cluster, you’ll notice a section that describes how you can utilize these results at DNAPainter.

While GEDmatch can’t automatically determine which of your matches are maternal and paternal, you can import them, by colored cluster, to DNAPainter where you can identify clusters to ancestors and paint them on your maternal and paternal chromosomes. I’ve written about how to use DNAPainter here.

Let’s scroll to the next section in your AutoSegment file.

Chromosome Segment Statistics

The next section of your file shows “Chromosome segment statistics per AutoSegment cluster.”

I need to take a minute here to describe the difference between:

  1. Colored clusters on your AutoCluster diagram, shown below, and
  2. Chromosome segment clusters or groups within each colored AutoSegment cluster

Remember, colored clusters are people, and you can match different people on different, sometimes multiple, chromosomes. Two people whose intersecting cell is colored triangulate on SOME segment but may also match on other segments that don’t triangulate with each other and you.

According to my “Chromosome segment statistics” report, my large orange AutoSegment cluster #1, above, includes:

  • 67 segments from all my matches
  • On five chromosomes (3, 5, 7, 10, 17)
  • That cluster into 8 separate chromosome segment clusters or groups within the orange cluster #1

This is much easier to visualize, so let’s take a look.

Chromosome Segment Clusters

Click on any cluster # in your report, above, to see the chromosome painting for that cluster. I’m clicking on my AutoSegment cluster #1 on the “Chromosome segment statistics” report that will reveal all of the segments in orange cluster #1 painted on my chromosomes.

The brightly colored painted segments show the triangulated segment locations on each chromosome. You can easily see the 8 different segment clusters in cluster #1.

Interestingly, three separate groups or chromosome clusters occur on chromosome 5. We’ll see in a few minutes that the segments in the third cluster on chromosome 5 overlaps with part of cluster #5. (Don’t confuse cluster number shown with a # and chromosome number. They are just coincidentally both 5 in this case.)

The next tool helps me visualize each of these segment clusters individually. Just scroll down.

You can mouse over the segment to view additional information, but I prefer the next tool because I can easily see how the DNA of the people who are included in this segment overlap with each other.

This view shows the individual chromosome clusters, or groups, contained entirely within the orange cluster #1. (Please note that you can adjust the column widths side to side by positioning the cursor at the edge of the column header and dragging.)

Fortunately, I recognize one of these matches, Deb, and I know exactly how she and I are related, and which ancestor we share – my great-grandparents.

Because these segments are triangulated, I know immediately that every one of these people share that segment with Deb and me because they inherited that segment of DNA from some common ancestor shared by me and Deb both.

To be very clear, these people may not share our exact same ancestor. They may share an ancestor upstream from Deb and my common ancestor. Regardless, these people, Deb, and I all share a segment I can assign at this point to my great-grandparents because it either came from them for everyone, or from an upstream ancestor who contributed it to one of my great-grandparents, who contributed it to me and Deb both.

Segment Clusters Entirely Linked

Clusters #2 and #3 are small and have common matches with people in cluster #1 as indicated by the grey cells, so let’s take a look.

I’m clicking on AutoSegment green cluster #2 which only has two cluster members.

I can see that the common triangulated segment between these two people and me occurs on chromosome 3.

This segment on chromosome 3 is entirely contained in green cluster #2, meaning no members of other clusters triangulate on this segment with me and these two people.

This can be a bit confusing, so let’s take it logically step by step.

Remember that the two people who triangulate in green cluster #2 also match people in orange cluster #1? However, the people from orange cluster #1 are NOT shown as members of green cluster #2.

This could mean that although the two people in the green cluster #2 match a couple of people in the orange cluster, they did not match the others, or they did not triangulate. This can be because of the minimum segment overlap threshold that is imposed.

So although there is a link between the people in the clusters, it is NOT sufficient for the green people to be included in the orange cluster and since the two matches triangulate on another segment, they become a separate green cluster.

In reality, you don’t need to understand exactly why members do or don’t fall into the clusters they do, you just need to understand generally how clustering and triangulation works. In essence, trust the tool if people are NOT included in multiple clusters. Click on each person individually to see which chromosomes they match you on, even if they don’t triangulate with others on all of those segments. At this point, I often run one-to-one matches, or other matching tools, to see exactly how people match me and each other.

However, if they ARE included in multiple partly linked clusters, that can be a HUGE bonus.

Let’s look at red cluster #3.

Segment Clusters Partly Linked

You can see that Mark, one of the members of red cluster #3 shares two triangulated segments, one on chromosome 4, and one on chromosome 10.

Mark and Glenn are members of cluster #3, but Glenn is not a member of the segment cluster/group on chromosome 4, only Iona and Mark.

Scrolling down, I can view additional information about the cluster members and the two segments that are held within red cluster #3.

Unlike green cluster #2 whose segment cluster/group is entirely confined to green cluster #2, red cluster #3 has NO segments entirely confined to members of red cluster #3.

Cluster #3 has two members, Mark and Glen. Mark and Glen, along with Val who is a member of orange cluster #1 triangulate on chromosome 10. Remember, I said that chromosome 10 would be important in a minute when we were discussing orange cluster #1. Now you know why.

This segment of chromosome 10 triangulates in both orange cluster #1 AND red cluster #3.

However, Mark, who is a red cluster #3 member also triangulates with Iona and me on a segment of chromosome 4. This segment also appears in AutoSegment brown cluster #4 on chromosome 4.

Now, the great news is that I know my earliest known ancestors with Iona, which means that I can assign this segment to my paternal great-great-grandparents.

If I can identify a common ancestor with some of these other people, I may be able to push segments back further in time to an earlier ancestral couple.

Identifying Common Ancestors

Of course, review each cluster’s members to see if you recognize any of your cousins.

If you don’t know anyone, how do you identify a common ancestor? You can email the person, of course, but GEDmatch also facilitates uploading GEDCOM files which are trees.

In your primary AutoSegment file, keep scrolling to see who has trees.

AutoSegment Cluster Information

If you continue to scroll down in your original HTML file, you’ll see AutoSegment Cluster Information.

For each cluster, all members are listed. It’s easy to see which people have uploaded trees. You can click to view and can hopefully identify an ancestor or at least a surname.

Click on “tree” to view your match’s entry, then on Pedigree to see their tree.

If your matches don’t have a tree, I suggest emailing and sharing what you do know. For example, I can tell my matches in cluster #1 that I know this line descends from Lazarus Estes and Elizabeth Vannoy, their birth and death dates and location, and encourage my match to view my tree which I have uploaded to GEDmatch.

If you happen to have a lot of matches with trees, you can create a tag group and run the AutoTree analysis on this tag group to identify common ancestors automatically. AutoTree is an amazing tool that identifies common ancestors in the trees of your matches, even if they aren’t in your tree. I wrote about AutoTree, here.

Pileup Regions

Whether you select “Remove Segments in Known Pileup Regions” or not when you select the options to run AutoSegment, you’ll receive a report that you can access by a link in the Explanation of AutoSegment Analysis section. The link is buried at the bottom of those paragraphs that I said not to skip, and many people don’t even see it. I didn’t at first, but it’s most certainly worth reviewing.

What Are Pileup Regions?

First, let’s talk about what pileup regions are, and why we observe them.

Some regions of the human genome are known to be more similar than others, for various reasons.

In these regions, people are more likely to match other people simply because we’re human – not specifically because we share a common ancestor.

EJ utilizes a list of pileup regions, based on the Li et al 2014 paper.

You may match other people on these fairly small segments because humans, generally, are more similar in these regions.

Many of those segments are too small to be considered a match by themselves, although if you happen to match on an adjacent segment, the pileup region could extend your match to appear to be more significant than it is.

If you select the “remove pileup segments” option, and you overlap any pileup region with 4.00 cM or larger, the entire matching segment that includes that region will be removed from the report no matter how large the matching segment is in total.

Here’s an example where the pileup region of 5.04 cM is right in the middle of a matching segment to someone. This entire 15.04 cM segment will be removed.

If those end segments are both 10 cM each instead of 5 cM, the segment will still be removed.

However, if the segment overlap with the pileup region is 3.99 cM or smaller, none of the resulting segment will be removed, so long as the entire segment is over the matching threshold in the first place. In the example above, if the AutoSegment threshold was 7 or 8 cM, the entire segment would be retained. If the matching threshold was 9 or greater, the segment would not have been included because of the threshold.

Of course, eight regions in the pileup chart are large enough to match without any additional adjacent segments if the match threshold is 7 cM and the overlap is exact. If the match threshold is 10 cM, only two pileup regions will possibly match by themselves. However, because those two regions are so large, we are more likely to see multiple matches in those regions.

Having a match in a pileup region does NOT invalidate that match. I have many matches in pileup regions that are perfectly valid, often extending beyond that region and attributable to an identified common ancestor.

You may also have pileup regions, in the regions shown in the chart and elsewhere, because of other genealogical reasons, including:

  • Endogamy, where your ancestors descend from a small, intermarried population, either through all or some of your ancestors. The Jewish population is probably the most well-known example of large-scale endogamy over a very long time period.
  • Pedigree collapse, where you descend from the same ancestors in multiple ways in a genealogical timeframe. Endogamy can reach far back in time. With pedigree collapse, you know who your ancestors are and how you descend, but with endogamy, you don’t.
  • Because you descend from an over-represented or over-tested group, such as the Acadians who settled in Nova Scotia in the early 1600s, intermarried and remained relatively isolated until 1755 when they were expelled. Their numerous descendants have settled in many locations. Acadian descendants often have a huge number of Acadian matches.
  • Some combination of all three of the above reasons. Acadians are a combination of both endogamy and pedigree collapse and many of their descendants have tested.

In my case, I have proportionally more Acadian matches than I have other matches, especially given that my Dutch and some of my German lines have few matches because they are recent immigrants with few descendants in the US. This dichotomy makes the proportional difference even more evident and glaring.

I want to stress here that pileup regions are not necessarily bad. In fact, they may provide huge clues to why you match a particular group of people.

Pileup Regions and Genealogy

In 2016, when Ancestry removed matches that involved personal pileup regions, segments that they felt were “too-matchy,” many of my lost matches were either Acadian or Mennonite/Brethren. Both groups are endogamous and experience pedigree collapse.

Over time, as I’ve worked with my DNA matches, painting my segments at DNAPainter, which marks pileup regions, I’ve come to realize that I don’t have more matches on segments spanning standard pileup regions indicated in the Li paper, nor are those matches unreliable.

An unreliable match might be signaled by people who match on that segment but descend from different unrelated common ancestors to me. Each segment tracks to one maternal and one paternal ancestral source, so if we find individuals matching on the same segment who claim descent from different ancestral lines on the same side, that’s a flag that something’s wrong. (That “something” could also be genealogy or descending from multiple ancestors.)

Therefore, after analyzing my own matching patterns, I don’t select the option to remove pileup segments and I don’t discount them. However, this may not be the right selection for everyone. Just remember, you can run the report as many times as your want, so nothing ventured, nothing gained.

Regardless of whether you select the remove pileup segments option or not, the report contents are very interesting.

Pileup Regions in the Report

Let’s take a look at Pileups in the AutoSegment report.

  • If I don’t select the option of removing pileup region segments, I receive a report that shows all of my segments.
  • If I do select the option to remove pileup region segments, here’s what my report says.

Based on the “remove pileup region segments” option selected, all segments should be removed in the pileup regions documented in the Li article if the match overlap is 4.00 cM or larger.

I want to be very clear here. The match itself is NOT removed UNLESS the pileup segment that IS removed causes the person not to be a match anymore. If that person still matches and triangulates on another segment over your selected AutoSegment threshold, those segments will still show.

I was curious about which of my chromosomes have the most matches. That’s exactly what the Pileup Report tells us.

According to the Pileup Report, my chromosome with the highest number of people matching is chromosome 5. The Y (vertical) axis shows the number of people that match on that segment, and the X axis across the bottom shows the match location on the chromosome.

You’ll recall that chromosome 5 was the chromosome from large orange AutoSegment cluster #1 with three distinct segment matches, so this makes perfect sense.

Sure enough, when I view my DNAPainter results, that first pileup region from about location 5-45 are Brethren matches (from my maternal grandfather) and the one from about 48-95 are Acadian matches (from my maternal grandmother.) This too makes sense.

Please note that chromosome 5 has no general pileup regions annotated in the Li table, so no segments would have been removed.

Let’s look at another example where some segments would be removed.

Based on the chromosome table from the Li paper, chromosome 15 has nearly back-to-back pileup regions from about 20-30 with almost 20 cM of DNA combined.

Let’s see what my Pileup Segment Removal Report for chromosome 15 shows.

No segment matches in this region are reported because I selected remove pileup regions.

The only way to tell how many segment matches were removed in this region is to run the report and NOT select the remove pileup segments option. I did that as a basis for comparison.

You can see that about three segments were removed and apparently one of those segments extended further than the other two. It’s also interesting that even though this is designated as a pileup region, I had fewer matches in this region than on other portions of the chromosome.

If I want to see who those segments belong to, I can just view my chromosome 15 results in the AutoSegment-segment-clusters tab in the spreadsheet view which is arranged neatly in chromosome order.

The only way to tell if matches in pileup regions are genealogically valid and relevant is to work with each match or group of matches and determine if they make sense. Does the match extend beyond the pileup region start and end edge? If so, how much? Can you identify a common ancestor or ancestral line, and if so, do the people who triangulate in that segment cluster makes sense?

Of course, my genealogy and therefore my experience will be different than other people’s. Anyone who descends primarily from an endogamous population may be very grateful for the “remove pileups” option. One size does NOT fit all. Fortunately, we have options.

You can run these reports as many times as you want, so you may want to run identical reports and compare a report that removes segments that occur in pileup regions with one that does not.

What’s Next?

For AutoSegment at GEDmatch to work most optimally, you’ll need to do three things:

  • If you don’t have one already, upload a raw DNA file from one of the testing vendors. Instructions here.
  • Upload a GEDCOM file. This allows you to more successfully run tools like AutoTree because your ancestors are present, and it helps other people too. Perhaps they will identify your common ancestor and contact you. You can always email your matches and suggest that they view your GEDCOM file to look for common ancestors or explain what you found using AutoTree. Anyone who has taken the time to learn about GEDmatch and upload a file might well be interested enough to make the effort to upload their GEDCOM file.
  • Convince relatives to upload their DNA files too or offer to upload for them. In my case, triangulating with my cousins is invaluable in identifying which ancestors are represented by each cluster.

If you have not yet uploaded a GEDCOM file to GEDmatch, now’s a great time while you’re thinking about it. You can see how useful AutoClusters and AutoSegment are, so give yourself every advantage in identifying common matches.

If you have a tree at Ancestry, you can easily download a copy and upload to GEDmatch. I wrote step-by-step instructions, here. Of course, you can upload any GEDCOM file from another source including your own desktop computer software.

You never know, using AutoSegment and AutoTree, you may just find common ancestors BETWEEN your matches that you aren’t aware of that might, just might, help you break down YOUR brick walls and find previously unknown ancestors.

AutoSegment tells you THAT you triangulate and exactly where. Now it’s up to you to figure out why.

Give AutoSegment at GEDmatch a try.

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Genealogy Research

Genetic Affairs – New AutoKinship Tool Predicts Relationships and Builds Genetic Trees

Genetic Affairs recently introduced a new tool – AutoKinship. Evert-Jan (EJ) Blom, the developer was kind enough to step through these results with me to assure that I’m explaining things correctly. Thanks EJ!

AutoKinship automatically predicts family trees and pathways that you may be related to your matches based on how they match you and each other. Not only is this important for genealogists trying to piece our family tree together, it’s indispensable for anyone searching for unknown ancestors, beginning with parents and walking right on up the tree for the closest several generations.

Right now, the automated AutoKinship tool is limited to 23andMe profiles, but will also work as a standalone tool where users can fill in the shared DNA information for their matches. MyHeritage, 23andMe, and GEDMatch provide centiMorgan information about how your matches also match each other. Here’s a tutorial for the standalone tool.

Unfortunately, Ancestry does not provide their customers with segment information, but fortunately, you can upload a copy of your Ancestry DNA file to MyHeritage, FamilyTreeDNA or GEDmatch, for free. You’ll find step-by-step instructions, here.

Automated AutoKinship Tool

After signing into to your Genetic Affairs account, assuming you have already set up your 23andMe profile at Genetic Affairs, click on “Run AutoKinship for 23andMe.”

I manage multiple profiles at 23andMe, so I need to click on “Profiles.”

Select the correct profile if you manage multiple kits at 23andMe.

You’ll see your various options that can be run for your 23andMe kit.

Select AutoKinship

If you select AutoKinship, you automatically receive an AutoCluster because AutoKinship is built on the AutoCluster functionality.

Make your selections. I recommend leaving these settings at the default, at least initially.

The default of 250 cM excludes your closest matches. You don’t want your closest matches because they will be members of too many clustered groups.

In my initial run, I made the mistake of changing the 50 cM lower threshold to 20 cM because I wanted more matches to be included. Unfortunately, the effect this had on my results was that my largest two clusters did not produce trees.

Hint: EJ states that the software tool works from the smallest cluster to the largest when producing trees. If you notice that your largest cluster, which is usually the first one displayed in the upper left hand corner (orange here), does not have associated trees, or some people are missing, that’s your clue that the AutoKinship ran out of server time to process and you need to raise either the minimum match threshold, in this case, 50 cM, or the minimum amount of DNA shared between your matches to each other, in this case, 10 cM.

You can also select between shared matches and triangulated groups. I selected shared matches, but I may well rerun this report with triangulated groups because that provides me with a great deal of even more useful information.

When you’re ready, click on the big green “you can’t miss it” Perform AutoCluster Analysis button.

Make a cup of coffee. Your report is processing. If your email doesn’t arrive, you can click on the little envelope in your Genetic Affairs profile and the report can be downloaded to your computer directly from that link.

Your Report Arrives!

You’ll receive a zip file in the email that you MUST SAVE TO YOUR COMPUTER to work correctly. You’ll see these files, but you can’t use them yet.

First, you MUST EXTRACT THE FILES from the zip file. My zip file displays the names of the file inside of the zipped file, but they are not extracted.

You must right click, as shown above, and then click on “Extract All” on a PC. Not sure what MAC users need to do but I think it autoextracts. If you click on some of the files in this article and they don’t load correctly, or say they aren’t present, that likely means:

  • You either forgot to save the file in the email to your computer
  • Or you failed to do the extract

The bottom two files are your normal AutoCluster visual html file and the same information in an excel file.

Click on the AutoCluster html file to activate.

Personally, I love watching the matches all fly into place in their clusters. This html file is going to be our home base, the file we’ll be operating from for all of the functions.

I have a total of 23 interrelated autoclusters. The question is, how are we all related to each other. You can read my article about AutoClusters and how they work here.

People who are members of more than one cluster are shown with those little grey squares signifying that they match people in two clusters, not just one cluster.

For example, one cluster might be my grandparents, but the second cluster might be my maternal great-great-grandfather. Membership in both clusters tells me that my matching DNA with those people in the second cluster probably descends from my great-great-grandfather. Some of the DNA matches in the first cluster assuredly also descend from that man, but some of them may descend from other related ancestors, like my maternal grandmother. It’s our job as genealogists to discern the connections, but the entire purpose of AutoKinship is to make that process much easier.

We are going to focus on the first few clusters to see what kinds of information Genetic Affairs can produce about these clusters. Notice that the first person in row 1 is related to the orange cluster, the green cluster, the purple and the brown clusters. That’s important information about that person, and also about the interrelationship of those clusters themselves and the ancestors they represent.

Remember, to be included in a grandparent cluster, that person’s DNA segment(s) must have descended from other ancestors, represented in other clusters. So you can expect one person to be found potentially in multiple clusters that serve to trace those common ancestors (and associated segments) back in time.

AutoKinship

The AutoKinship portion of this tool creates hypothetical trees based on relationships of you to each person in the cluster, and to the other cluster members to each other.

If you’re thinking triangulation, you’re right. I selected matches, not triangulated groups which is also an option. Some people do triangulate, but some people may match each other on different segments. Right now, it’s a jumble of hints, but we’ll sort some of this out.

If you scroll down in your html file, below your cluster, and below the explanation (which you should read,) you’ll see the AutoKinship verbiage.

I want to do a quick shout-out to Brit Nicholson, the statistician that works with EJ on probabilities of relationships for this tool and describes his methodology, here.

AutoKinship Table

You’ll see the AutoKinship Table that includes a link for each cluster that could be assembled into a potential tree.

Click on the cluster you wish to view.

In my case, clusters 1 through 5 are closely related to each other based on the common members in each cluster. I selected cluster 1.

Your most probable tree for that cluster will be displayed.

I’m fortunate that I recognized three of my third cousins. AutoKinship constructed a probable genetic pedigree, but I’ve overlayed what I know to be the correct pedigree.

With the exception of one person, this AutoKinship tree is accurate to the best of my knowledge. A slot for Elizabeth, the mother of William George Estes and the daughter of Joel is missing. I probably know why. I match two of my cousins with a higher than expected amount of DNA which means that I’m shown “closer” in genetic distance that I normally would be for that relationship level.

In one case, Charles and I share multiple ancestors. In the other case, I don’t know why I match Everett on so much more DNA than his brother Carl or our other cousin, Vianna. Regardless, I do.

In one other instance, there’s a half-relationship that throws a wrench into the tree. I know that, but it’s very difficult to factor half-relationships into tree building without prior knowledge.

If you continue to scroll down, you’ll see multiple options for trees for this cluster.

DNA Matrix

Below that, you’ll see a wonderful downloadable DNA matrix of how everyone in the cluster shares DNA with everyone else in the cluster.

At this point, exit from cluster one and return to your original cluster file that shows your cluster matrix.

Beneath the AutoKinship table, you’ll see AutoCluster Cluster Information.

AutoCluster Cluster Information

Click on any one of those people. I’m selecting Everett because I know how we are related.

Voila, a new cluster configuration forms.

I can see all of the people I match in common with Everett in each cluster. This tells me two things:

  • Which clusters are related to this line. In particular, the orange cluster, green, red, purple, brown, magenta and dark grey clusters. If you mouse over each cell in the cluster, more information is provided.
  • The little helix in each cell tells you that those two people triangulate with each other and the tester. How cool is that?!!

Note that you can display this cluster in 4 different ways.

Return again to your main autocluster page and scroll down once again.

This just might be my favorite part.

Chromosome Segments

You can import chromosome segment information into DNAPainter – instructions here.

What you’ll see next is the clusters painted on your chromosomes. I love this!!!

Of course, Genetic Affairs can’t tell you which side is maternal and which is paternal. You’ll need to do that yourself after you import into DNAPainter.

Just beneath this painting, you’ll see a chart titled Chromosome segment statistics per AutoCluster cluster.

I’m only showing the first couple as an example.

Click on one of links. I’m selecting cluster 1.

Cluster 1 has painted portions of each chromosome, but I’m only displaying chromosomes 1-7 here.

Following the painting is a visual display of each overlap region by cluster, by overlapping segment on each chromosome.

You can clearly see where these segments overlap with each other!

Surname Enrichment

If you select the surname enrichment option, you’ll receive two additional features in your report.

Please note that I ran this option separately at a different time, so the cluster members and clusters themselves do not necessarily correlate with the examples above.

The Enriched Surname section of your report shows surnames in common found between the matches in each specific cluster.

Keep in mind, this does NOT just mean surnames in common with YOUR surname list, assuming you’ve entered your surnames at 23andMe. (If you haven’t please do so now.) 23andMe does not support user trees, so your entered surnames are all that can be utilized when comparing information from your matches.

These are surnames that are found more than once among your matches. I’ve framed the ones in red that I recognize as being found in my tree, and I’ve framed the ones in black that I recognize as being “married in.” In other words, some people may descend through children of my ancestors who married people with that black bracketed surname.

I can tell you immediately, based on these surnames, that the first cluster is the cluster formed around my great-great-grandparents, Joel Vannoy and his wife, Phebe Crumley.

Cluster 6 is less evident, but Anderson might be connected to the Vannoy family. I’ll need to view the common matches in that cluster at 23andMe and look for additional clues.

Cluster 9 is immediately evident too. Ferverda is Hiram Ferverda, my great-grandfather and Eva Miller is his wife.

Cluster 10 is probably the Miller line as well. Indiana is a location in this case, not a surname.

Click on “Detailed Surname Table” for more information, as shown below.

Each group of people that shares any surname is shown in a table together. In this case, these three people, who I happen to know are brothers, all share these surnames. The surnames they also share with me are shown with red boxes. The other surnames are shared only with each other and no one else in the cluster. I know they aren’t shared with me because I know my tree.

While your initial reaction may be that this isn’t terribly useful, it is actually a HUGE gift. Especially if you find a cluster you aren’t familiar with.

Mystery Cluster

A mystery cluster is an opportunity to break down a brick wall. This report tells you which people to view on your match list who share that surname. My first step is to use that list and see who I match in common with each person at 23andMe.

My relatives in common with my Cluster 10 matches include my close Ferverda cousins who descend from our common Miller ancestor, plus a few Miller cousins. This confirms that this cluster does indeed originate in the Miller line.

Not everyone in that cluster shares the surname Miller. That might be a good thing.

I have a long-standing brick wall with Magdalena (surname unknown) who was married to Philip Jacob Miller, my 5-times great-grandparents. My cousins through that couple, at my same generation, would be about 6th cousins.

These matches are matching me at the approximate 4th cousin level or more distantly, so it’s possible that at least some of these matches COULD be through Magdalena’s family. In that case, I certainly would not recognize the common surnames. Therefore, it’s imperative that I chase these leads. I can also adjust the matching threshold to obtain more matches, hopefully, in this cluster, and run the report again.

Are you in love with Autokinship and its associated features yet? I am!

Summary

Wow is all I can say. There’s enough in this one report to keep me busy for days, especially since 23andMe does not support a tree function in the traditional genealogical sense.

I have several matches that I have absolutely no idea how they are related to me. This helps a great deal and allows to me systematically approach tree-building or identifying ancestors.

You can see if 23andMe has predicted these relationships in the same way, but other than messaging your matches, or finding them at another vendor who does support a tree, there’s no way to know if either 23andMe’s autogenerated tree or the Genetic Affairs trees are accurate.

What Genetic Affairs provides that 23andMe does not is composite information in one place – as a group in a cluster. You don’t have to figure out who matches whom one by one and create your own matrix. (Yes, I used to do that.)

You can also import the Genetic Affairs information into DNAPainter to make further use of these segments. I’ve written about using DNAPainter, here.

Once you’ve identified how one person in any cluster connects, you’ve found your lever to unlock the identity of the ancestors whose DNA is represented in that particular cluster – and an important clue/link to associated clusters as well.

If you don’t recognize these cousins at 23andMe, look for common surnames on your DNA Relatives match list, or see if a known close relative on your maternal or paternal side matches these people found in a cluster. Click on each match at 23andMe to see if they have provided notes, surnames, locations or even a link to a tree at another vendor.

Don’t forget, you can also select the “Based on Triangulated Groups” option instead of the “Based on Shared Matches” option initially.

Run A Report

If you have tested at 23andMe, give the Genetic Affairs AutoKinship report a try.

Is it accurate for you? Have you gained insight? Identified how people are related to you? Are there any surprises?

Do you have a mystery cluster? I hope so, because an answer just might be hiding there.

If you’d like to read more about Genetic Affairs tools, click here for my free repository of Genetic Affairs articles.

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Genealogy Research

A Triangulation Checklist Born From the Question; “Why NOT Use Close Relatives for Triangulation?”

One of my readers asked why we don’t use close relatives for triangulation.

This is a great question because not using close relatives for triangulation seems counter-intuitive.

I used to ask my kids and eventually my students and customers if they wanted the quick short answer or the longer educational answer.

The short answer is “because close relatives are too close to reliably form the third leg of the triangle.” Since you share so much DNA with close relatives, someone matching you who is identical by chance can also match them for exactly the same reason.

If you trust me and you’re good with that answer, wonderful. But I hope you’ll keep reading because there’s so much to consider, not to mention a few gotchas. I’ll share my methodology, techniques, and workarounds.

We’ll also discuss absolutely wonderful ways to utilize close relatives in the genetic genealogical process – just not for triangulation.

At the end of this article, I’ve provided a working triangulation checklist for you to use when evaluating your matches.

Let’s go!

The Step-by-Step Educational Answer😊

Some people see “evidence” they believe conflicts with the concept that you should not use close relatives for triangulation. I understand that, because I’ve gone down that rathole too, so I’m providing the “educational answer” that explains exactly WHY you should not use close relatives for triangulation – and what you should do.

Of course, we need to answer the question, “Who actually are close relatives?”

I’ll explain the best ways to best utilize close relatives in genetic genealogy, and why some matches are deceptive.

You’ll need to understand the underpinnings of DNA inheritance and also of how the different vendors handle DNA matching behind the scenes.

The purpose of autosomal DNA triangulation is to confirm that a segment is passed down from a particular ancestor to you and a specific set of your matches.

Triangulation, of course, implies 3, so at least three people must all match each other on a reasonably sized portion of the same DNA segment for triangulation to occur.

Matching just one person only provides you with one path to that common ancestor. It’s possible that you match that person due to a different ancestor that you aren’t aware of, or due to chance recombination of DNA.

It’s possible that your or your match inherited part of that DNA from your maternal side and part from your paternal side, meaning that you are matching that other person’s DNA by chance.

I wrote about identical by descent (IBD), which is an accurate genealogically meaningful match, and identical by chance (IBC) which is a false match, in the article Concepts – Identical by…Descent, State, Population and Chance.

I really want you to understand why close relatives really shouldn’t be used for triangulation, and HOW close relative matches should be used, so we’re going to discuss all of the factors that affect and influence this topic – both the obvious and little-understood.

  • Legitimate Matches
  • Inheritance and Triangulation
  • Parental Cross-Matching
  • Parental Phasing
  • Automatic Phasing at FamilyTreeDNA
  • Parental Phasing Caveats
  • Pedigree Collapse
  • Endogamy
  • How Many Identical-by-Chance Matches Will I Have?
  • DNA Doesn’t Skip Generations (Seriously, It Doesn’t)
  • Your Parents Have DNA That You Don’t (And How to Use It)
  • No DNA Match Doesn’t Mean You’re Not Related
  • Imputation
  • Ancestry Issues and Workarounds
  • Testing Close Relatives is VERY Useful – Just Not for Triangulation
  • Triangulated Matches
  • Building Triangulation Evidence – Ingredients and a Recipe
  • Aunts/Uncles
  • Siblings
  • How False Positives Work and How to Avoid Them
  • Distant Cousins Are Best for Triangulation & Here’s Why
  • Where Are We? A Triangulation Checklist for You!
  • The Bottom Line

Don’t worry, these sections are logical and concise. I considered making this into multiple articles, but I really want it in one place for you. I’ve created lots of graphics with examples to help out.

Let’s start by dispelling a myth.

DNA Doesn’t Skip Generations!

Recently, someone emailed to let me know that they had “stopped listening to me” in a presentation when I said that if a match did not also match one of your parents, it was a false match. That person informed me that they had worked on their tree for three years at Ancestry and they have “proof” of DNA skipping generations.

Nope, sorry. That really doesn’t happen, but there are circumstances when a person who doesn’t understand either how DNA works, or how the vendor they are using presents DNA results could misunderstand or misinterpret the results.

You can watch my presentation, RootsTech session, DNA Triangulation: What, Why and How, for free here. I’m thrilled that this session is now being used in courses at two different universities.

DNA really doesn’t skip generations. You CANNOT inherit DNA that your parents didn’t have.

Full stop.

Your children cannot inherit DNA from you that you don’t carry. If you don’t have that DNA, your children and their descendants can’t have it either, at least not from you. They of course do inherit DNA from their other parent.

I think historically, the “skipping generations” commentary was connected to traits. For example, Susie has dimples (or whatever) and so did her maternal grandmother, but her mother did not, so Susie’s dimples were said to have “skipped a generation.” Of course, we don’t know anything about Susie’s other grandparents, if Susie’s parents share ancestors, recessive/dominant genes or even how many genetic locations are involved with the inheritance of “dimples,” but I digress.

DNA skipping generations is a fallacy.

You cannot legitimately match someone that your parent does not, at least not through that parent’s side of the tree.

But here’s the caveat. You can’t match someone one of your parents doesn’t with the rare exception of:

  • Relatively recent pedigree collapse that occurs when you have the same ancestors on both sides of your tree, meaning your parents are related, AND
  • The process of recombination just happened to split and recombine a segment of DNA in segments too small for your match to match your parents individually, but large enough when recombined to match you.

We’ll talk about that more in a minute.

However, the person working with Ancestry trees can’t make this determination because Ancestry doesn’t provide segment information. Ancestry also handles DNA differently than other vendors, which we’ll also discuss shortly.

We’ll review all of this, but let’s start at the beginning and explain how to determine if our matches are legitimate, or not.

Legitimate Matches

Legitimate matches occur when the DNA of your ancestor is passed from that ancestor to their descendants, and eventually to you and a match in an unbroken pathway.

Unbroken means that every ancestor between you and that ancestor carried and then passed on the segment of the ancestor’s DNA that you carry today. The same is true for your match who carries the same segment of DNA from your common ancestor.

False positive matches occur when the DNA of a male and female combine randomly to look like a legitimate match to someone else.

Thankfully, there are ways to tell the difference.

Inheritance and Triangulation

Remember, you inherit two copies of each of your chromosomes 1-22, one copy from your mother and one from your father. You inherit half of the DNA that each parent carries, but it’s mixed together in you so the labs can’t readily tell which nucleotide, A, C, T, or G you received from which parent. I’m showing your maternal and paternal DNA in the graphic below, stacked neatly together in a column – but in reality, it could be AC in one position and CA in the next.

For matching all that matters is the nucleotide that matches your match is present in one of those two locations. In this case, A for your mother’s side and C for your father’s side. If you’re interested, you can read more about that in the article, Hit a Genealogy Home Run Using Your Double-Sided Two-Faced Chromosomes While Avoiding Imposters.

You can see in this example that you inherited all As from your Mom and all Cs from your Dad.

  • A legitimate maternal match would match you on all As on this particular example segment.
  • A legitimate paternal match would match you on all Cs on this particular segment.
  • A false positive match will match you on some random combination of As and Cs that make it look like they match you legitimately, but they don’t.
  • A false positive match will NOT match either your mother or your father.

To be very clear, technically a false positive match DOES match your DNA – but they don’t match your DNA because you share a common ancestor with your match. They match you because random recombination on their side causes you to match each other by chance.

In other words, if part of your DNA came from your Mom’s side and part from your Dad’s but it randomly fell in the correct positional order, you’d still match someone whose DNA was from only their mother or father’s side. That’s exactly the situation shown above and below.

Looking at our example again, it’s evident that your identical by chance (IBC) match’s A locations (1, 3, 5, 7 & 9) will match your Mom. C locations (2, 4, 6 8, & 10) will match your Dad, but the nonmatching segments interleaved in-between that match alternating parents will prevent your match from matching either of your parents. In other words, out of 10 contiguous locations in our example, your IBC match has 5 As alternated with 5 Cs, so they won’t match either of your parents who have 10 As or 10 Cs in a row.

This recombination effect can work in either direction. Either or both matching people’s DNA could be randomly mixed causing them to match each other, but not their parents.

Regardless of whose DNA is zigzagging back and forth between maternal and paternal, the match is not genealogical and does not confirm a common ancestor.

This is exactly why triangulation works and is crucial.

If you legitimately match a third person, shown below, on your maternal side, they will match you, your first legitimate maternal match, and your Mom because they carry all As. But they WON’T match the person who is matching you because they are identical by chance, shown in grey below.

The only person your identical by chance match matches in this group is you because they match you because of the chance recombination of parental DNA.

That third person WILL also match all other legitimate maternal matches on this segment.

In the graphic above, we see that while the grey identical by chance person matches you because of the random combination of As from your mother and Cs from your father, your legitimate maternal matches won’t match your identical by chance match.

This is the first step in identifying false matches.

Parental Cross-Matching

Removing the identical by chance match, and adding in the parents of your legitimate maternal match, we see that your maternal match, above, matches you because you both have all As inherited from one parent, not from a combination of both parents.

We know that because we can see the DNA of both parents of both matches in this example.

The ideal situation occurs when two people match and they have both had their parents tested. We need to see if each person matches the other person’s parents.

We can see that you do NOT match your match’s father and your match does NOT match your father.

You do match your match’s mother and your match does match your mother. I refer to this as Parental Cross-matching.

Your legitimate maternal matches will also match each other and your mother if she is available for testing.

All the people in yellow match each other, while the two parents in gray do not match any of your matches. An entire group of legitimate maternal matches on this segment, no matter how many, will all match each other.

If another person matches you and the other yellow people, you’ll still need to see if you match their parents, because if not, that means they are matching you on all As because their two parents DNA combined just happened, by chance, to contribute an A in all of those positions.

In this last example, your new match, in green, matches you, your legitimate match and both of your mothers, BUT, none of the four yellow people match either of the new match’s parents. You can see that the new green match inherited their As from the DNA of their mother and father both, randomly zigzagging back and forth.

The four yellow matches phase parentally as we just proved with cross matching to parents. The new match at first glance appears to be a legitimate match because they match all of the yellow people – but they aren’t because the yellow people don’t match the green person’s parents.

To tell the difference between legitimate matches and identical by chance matches, you need two things, in order.

  • Parental matching known as parental phasing along with parental cross-matching, if possible, AND
  • Legitimate identical by descent (IBD) triangulated matches

If you have the ability to perform parental matching, called phasing, that’s the easiest first step in eliminating identical by chance matches. However, few match pairs will have parents for everyone. You can use triangulation without parental phasing if parents aren’t available.

Let’s talk about both, including when and how close relatives can and cannot be used.

Parental Phasing

The technique of confirming your match to be legitimate by your match also matching one of your parents is called parental phasing.

If we have the parents of both people in a match pair available for matching, we can easily tell if the match does NOT match either parent. That’s Parental Cross Matching. If either match does NOT match one of the other person’s parents, the match is identical by chance, also known as a false positive.

See how easy that was!

If you, for example, is the only person in your match pair to have parents available, then you can parentally phase the match on your side if your match matches your parents. However, because your match’s parents are unavailable, your match to them cannon tbe verified as legitimate on their side. So you are not phased to their parents.

If you only have one of your parents available for matching, and your match does not match that parent, you CANNOT presume that because your match does NOT match that parent, the match is a legitimate match for the other, missing, parent.

There are four possible match conditions:

  • Maternal match
  • Paternal match
  • Matches neither parent which means the match is identical by chance meaning a false positive
  • Matches both parents in the case of pedigree collapse or endogamy

If two matching people do match one parent of both matches (parental cross-matching), then the match is legitimate. In other words, if we match, I need to match one of your parents and you need to match one of mine.

It’s important to compare your matches’ DNA to generationally older direct family members such as parents or grandparents, if that’s possible. If your grandparents are available, it’s possible to phase your matches back another generation.

Automatic Phasing at FamilyTreeDNA

FamilyTreeDNA automatically phases your matches to your parents if you test that parent, create or upload a GEDCOM file, and link your test and theirs to your tree in the proper places.

FamilyTreeDNA‘s Family Matching assigns or “buckets” your matches maternally and paternally. Matches are assigned as maternal or paternal matches if one or both parents have tested.

Additionally, FamilyTreeDNA uses triangulated matches from other linked relatives within your tree even if your parents have not tested. If you don’t have your parents, the more people you identify and link to your tree in the proper place, the more people will be assigned to maternal and paternal buckets. FamilyTreeDNA is the only vendor that does this. I wrote about this process in the article, Triangulation in Action at Family Tree DNA.

Parental Phasing Caveats

There are very rare instances where parental phasing may be technically accurate, but not genealogically relevant. By this, I mean that a parent may actually match one of your matches due to endogamy or a population level match, even if it’s considered a false positive because it’s not relevant in a genealogical timeframe.

Conversely, a parent may not match when the segment is actually legitimate, but it’s quite rare and only when pedigree collapse has occurred in a very specific set of circumstances where both parents share a common ancestor.

Let’s take a look at that.

Pedigree Collapse

It’s not terribly uncommon in the not-too-distant past to find first cousins marrying each other, especially in rather closely-knit religious communities. I encounter this in Brethren, Mennonite and Amish families often where the community was small and out-marrying was frowned upon and highly discouraged. These families and sometimes entire church congregations migrated cross-country together for generations.

When pedigree collapse is present, meaning the mother and father share a common ancestor not far in the past, it is possible to inherit half of one segment from Mom and the other half from Dad where those halves originated with the same ancestral couple.

For example, let’s say the matching segment between you and your match is 12 cM in length, shown below. You inherited the blue segment from your Dad and the neighboring peach segment from Mom – shown just below the segment numbers. You received 6 cM from both parents.

Another person’s DNA does match you, shown in the bottom row, but they are not shown on the DNA match list of either of your parents. That’s because the DNA segments of the parents just happened to recombine in 6 cM pieces, respectively, which is below the 7 cM matching threshold of the vendor in this example.

If the person matched you at 12 cM where you inherited 8 cM from one parent and 4 from the other, that person would show on one parent’s match list, but not the other. They would not be on the parent’s match list who contributed only 4 cM simply because the DNA divided and recombined in that manner. They would match you on a longer segment than they match your parent at 8 cM which you might notice as “odd.”

Let’s look at another example.

click to enlarge image

If the matching segment is 20 cM, the person will match you and both of your parents on different pieces of the same segment, given that both segments are above 7 cM. In this case, your match who matches you at 20 cM will match each of your parents at 10 cM.

You would be able to tell that the end location of Dad’s segment is the same as the start location of Mom’s segment.

This is NOT common and is NOT the “go to” answer when you think someone “should” match your parent and does not. It may be worth considering in known pedigree collapse situations.

You can see why someone observing this phenomenon could “presume” that DNA skipped a generation because the person matches you on segments where they don’t match your parent. But DNA didn’t skip anything at all. This circumstance was caused by a combination of pedigree collapse, random division of DNA, then random recombination in the same location where that same DNA segment was divided earlier. Clearly, this sequence of events is not something that happens often.

If you’ve uploaded your DNA to GEDmatch, you can select the “Are your parents related?” function which scans your DNA file for runs of homozygosity (ROH) where your DNA is exactly the same in both parental locations for a significant distance. This suggests that because you inherited the exact same sequence from both parents, that your parents share an ancestor.

If your parents didn’t inherit the same segment of DNA from both parents, or the segment is too short, then they won’t show as “being related,” even if they do share a common ancestor.

Now, let’s look at the opposite situation. Parental phasing and ROH sometimes do occur when common ancestors are far back in time and the match is not genealogically relevant.

Endogamy

I often see non-genealogical matching occur when dealing with endogamy. Endogamy occurs when an entire population has been isolated genetically for a long time. In this circumstance, a substantial part of the population shares common DNA segments because there were few original population founders. Much of the present-day population carries that same DNA. Many people within that population would match on that segment. Think about the Jewish community and indigenous Americans.

Consider our original example, but this time where much of the endogamous population carries all As in these positions because one of the original founders carried that nucleotide sequence. Many people would match lots of other people regardless of whether they are a close relative or share a distant ancestor.

People with endogamous lines do share relatives, but that matching DNA segment originated in ancestors much further back in time. When dealing with endogamy, I use parental phasing as a first step, if possible, then focus on larger matches, generally 20 cM or greater. Smaller matches either aren’t relevant or you often can’t tell if/how they are.

At FamilyTreeDNA, people with endogamy will find many people bucketed on the “Both” tab meaning they triangulate with people linked on both sides of the tester’s tree.

An example of a Jewish person’s bucketed matches based on triangulation with relatives linked in their tree is shown above.

Your siblings, their children, and your children will be related on both your mother’s and father’s sides, but other people typically won’t be unless you have experienced either pedigree collapse where you are related both maternally and paternally through the same ancestors or you descend from an endogamous population.

How Many Identical-by-Chance Matches Will I Have?

If you have both parents available to test, and you’re not dealing with either pedigree collapse or endogamy, you’ll likely find that about 15-20% of your matches don’t match your parents on the same segment and are identical by chance.

With endogamy, you’ll have MANY more matches on your endogamous lines and you’ll have some irrelevant matches, often referred to as “false positive” matches even though they technically aren’t, even using parental phasing.

Your Parents Have DNA That You Don’t

Sometimes people are confused when reviewing their matches and their parent’s match to the same person, especially when they match someone and their parent matches them on a different or an additional segment.

If you match someone on a specific segment and your parents do not, that’s a false positive FOR THAT SEGMENT. Every segment has its own individual history and should be evaluated individually. You can match someone on two segments, one from each parent. Or three segments, one from each parent and one that’s identical by chance. Don’t assume.

Often, your match will match both you and your parent on the same segment – which is a legitimate parentally phased match.

But what if your match matches your parent on a different segment where they don’t match you? That’s a false positive match for you.

Keep in mind that it is possible for one of your matches to match your parent on a separate or an additional segment that IS legitimate. You simply didn’t inherit that particular segment from your parent.

That’s NOT the same situation as someone matching you that does NOT match one of your parents on the same segment – which is an identical by chance or false match.

Your parent having a match that does not match you is the reverse situation.

I have several situations where I match someone on one segment, and they match my parent on the same segment. Additionally, that person matches my parent on another segment that I did NOT inherit from that parent. That’s perfectly normal.

Remember, you only inherit half of your parent’s DNA, so you literally did NOT inherit the other half of their DNA. Your mother, for example, should have twice as many matches as you on her side because roughly half of her matches won’t match you.

That’s exactly why testing your parents and close family members is so critical. Their matches are as valid and relevant to your genealogy as your own. The same is true for other relatives, such as aunts and uncles with whom you share ALL of the same ancestors.

You need to work with your family member’s matches that you don’t share.

No DNA Match Doesn’t Mean You’re Not Related

Some people think that not matching someone on a DNA test is equivalent to saying they aren’t related. Not sharing DNA doesn’t mean you’re not related.

People are often disappointed when they don’t match someone they think they should and interpret that to mean that the testing company is telling them they “aren’t related.” They are upset and take issue with this characterization. But that’s not what it means.

Let’s analyze this a bit further.

First, not sharing DNA with a second cousin once removed (2C1R) or more distant does NOT mean you’re NOT related to that person. It simply means you don’t share any measurable DNA ABOVE THE VENDOR THRESHOLD.

All known second cousins match, but about 10% of third cousins don’t match, and so forth on up the line with each generation further back in time having fewer cousins that match each other.

If you have tested close relatives, check to see if that cousin matches your relatives.

Second, it’s possible to match through the “other” or unexpected parent. I certainly didn’t think this would be the case in my family, because my father is from Appalachia and my mother’s family is primarily from the Netherlands, Germany, Canada, and New England. But I was wrong.

All it took was one German son that settled in Appalachia, and voila, a match through my mother that I surely thought should have been through my father’s side. I have my mother’s DNA and sure enough, my match that I thought should be on my father’s side matches Mom on the same segment where they match me, along with several triangulated matches. Further research confirmed why.

I’ve also encountered situations where I legitimately match someone on both my mother’s and father’s side, on different segments.

Third, imputation can be important for people who don’t match and think they should. Imputation can also cause matching segment length to be overreported.

Ok, so what’s imputation and why do I care?

Imputation

Every DNA vendor today has to use some type of imputation.

Let me explain, in general, what imputation is and why vendors use it.

Over the years, DNA processing vendors who sell DNA chips to testing companies have changed their DNA chips pretty substantially. While genealogical autosomal tests test about 700,000 DNA locations, plus or minus, those locations have changed over time. Today, some of these chips only have 100,000 or so chip locations in common with chips either currently or previously utilized by other vendors.

The vendors who do NOT accept uploads, such as 23andMe or Ancestry, have to develop methods to make their newest customers on their DNA processing vendor’s latest chip compatible with their first customer who was tested on their oldest chip – and all iterations in-between.

Vendors who do accept transfers/uploads from other vendors have to equalize any number of vendors’ chips when their customers upload those files.

Imputation is the scientific way to achieve this cross-platform functionality and has been widely used in the industry since 2017.

Imputation, in essence, fills in the blanks between tested locations with the “most likely” DNA found in the human population based on what’s surrounding the blank location.

Think of the word C_T. There are a limited number of letters and words that are candidates for C_T. If you use the word in a sentence, your odds of accuracy increase dramatically. Think of a genetic string of nucleotides as a sentence.

Imputation can be incorrect and can cause both false positive and false negative matches.

For the most part, imputation does not affect close family matches as much as more distant matches. In other words, imputation is NOT going to cause close family members not to match.

Imputation may cause more distant family members not to match, or to have a false positive match when imputation is incorrect.

Imputation is actually MUCH less problematic than I initially expected.

The most likely effect of imputation is to cause a match to be just above or below the vendor threshold.

How can we minimize the effects of imputation?

  • Generally, the best result will be achieved if both people test at the same vendor where their DNA is processed on the same chip and less imputation is required.
  • Upload the results of both people to both MyHeritage and FamilyTreeDNA. If your match results are generally consistent at those vendors, imputation is not a factor.
  • GEDmatch does not use imputation but attempts to overcome files with low overlapping regions by allowing larger mismatch areas. I find their matches to be less accurate than at the various vendors.

Additionally, Ancestry has a few complicating factors.

Ancestry Issues

AncestryDNA is different in three ways.

  • Ancestry doesn’t provide segment information so it’s impossible to triangulate or identify the segment or chromosome where people match. There is no chromosome browser or triangulation tool.
  • Ancestry down-weights and removes some segments in areas where they feel that people are “too matchy.” You can read Ancestry’s white papers here and here.

These “personal pileup regions,” as they are known, can be important genealogically. In my case, these are my mother’s Acadian ancestors. Yes, this is an endogamous population and also suffers from pedigree collapse, but since this is only one of my mother’s great-grandparents, this match information is useful and should not be removed.

  • Ancestry doesn’t show matches in common if the shared segments are less than 20cM. Therefore, you may not see someone on a shared match list with a relative when they actually are a shared match.

If two people both match a third person on less than a 20 cM segment at Ancestry, the third person won’t appear on the other person’s shared match list. So, if I match John Doe on 19 cM of DNA, and I looked at the shared matches with my Dad, John Doe does NOT appear on the shared match list of me and my Dad – even though he is a match to both of us at 19 cM.

The only way to determine if John Doe is a shared match is to check my Dad’s and my match list individually, which means Dad and I will need to individually search for John Doe.

Caveat here – Ancestry’s search sometimes does not work correctly.

Might someone who doesn’t understand that the shared match list doesn’t show everyone who shares DNA with both people presume that the ancestral DNA of that ancestor “skipped a generation” because John Doe matches me with a known ancestor, and not Dad on our shared match list? I mean, wouldn’t you think that a shared match would be shown on a tab labeled “Shared Matches,” especially since there is no disclaimer?

Yes, people can be forgiven for believing that somehow DNA “skipped” a generation in this circumstance, especially if they are relatively inexperienced and they don’t understand Ancestry’s anomalies or know that they need to or how to search for matches individually.

Even if John Doe does match me and Dad both, we still need to confirm that it’s on the same segment AND it’s a legitimate match, not IBC. You can’t perform either of these functions at Ancestry, but you can elsewhere.

Ancestry WorkArounds

To obtain this functionality, people can upload their DNA files for free to both FamilyTreeDNA and MyHeritage, companies that do provide full shared DNA reporting (in common with) lists of ALL matches and do provide segment information with chromosome browsers. Furthermore, both provide triangulation in different ways.

Matching is free, but an inexpensive unlock is required at both vendors to access advanced tools such as Family Matching (bucketing) and triangulation at Family Tree DNA and phasing/triangulation at MyHeritage.

I wrote about Triangulation in Action at FamilyTreeDNA, here.

MyHeritage actually brackets triangulated segments for customers on their chromosome browser, including parents, so you get triangulation and parental phasing at the same time if you and your parent have both tested or uploaded your DNA file to MyHeritage. You can upload, for free, here.

In this example, my mother is matching to me in red on the entire length of chromosome 18, of course, and three other maternal cousins triangulate with me and mother inside the bracketed portion of chromosome 18. Please note that if any one of the people included in the chromosome browser comparison do not triangulate, no bracket is drawn around any others who do triangulate. It’s all or nothing. I remove people one by one to see if people triangulate – or build one by one with my mother included.

I wrote about Triangulation in Action at MyHeritage, here.

People can also upload to GEDmatch, a third-party site. While GEDmatch is less reliable for matching, you can adjust your search thresholds which you cannot do at other vendors. I don’t recommend routinely working below 7 cM. I occasionally use GEDmatch to see if a pedigree collapse segment has recombined below another vendor’s segment matching threshold.

Do NOT check the box to prevent hard breaks when selecting the One-to-One comparison. Checking that box allows GEDmatch to combine smaller matching segments into mega-segments for matching.

I wrote about Triangulation in Action at GEDmatch, here.

Transferring/Uploading Your DNA 

If you want to transfer your DNA to one of these vendors, you must download the DNA file from one vendor and upload it to another. That process does NOT remove your DNA file from the vendor where you tested, unless you select that option entirely separately.

I wrote full step-by-step transfer/upload instructions for each vendor, here.

Testing Close Relatives Is VERY Useful – Just Not for Triangulation

Of course, your best bet if you don’t have your parents available to test is to test as many of your grandparents, great-aunts/uncles, aunts, and uncles as possible. Test your siblings as well, because they will have inherited some of the same and some different segments of DNA from your parents – which means they carry different pieces of your ancestors’ DNA.

Just because close relatives don’t make good triangulation candidates doesn’t mean they aren’t valuable. Close relatives are golden because when they DO share a match with you, you know where to start looking for a common ancestor, even if your relative matches that person on a different segment than you do.

Close relatives are also important because they will share pieces of your common ancestor’s DNA that you don’t. Their matches can unlock the answers to your genealogy questions.

Ok, back to triangulation.

Triangulated Matches

A triangulated match is, of course, when three people all descended from a common ancestor and match each other on the same segment of DNA.

That means all three people’s DNA matches each other on that same segment, confirming that the match is not by chance, and that segment did descend from a common ancestor or ancestral couple.

But, is this always true? You’re going to hate this answer…

“It depends.”

You knew that was coming, didn’t you! 😊

It depends on the circumstances and relationships of the three people involved.

  • One of those three people can match the other two by chance, not by descent, especially if two of those people are close relatives to each other.
  • Identical by chance means that one of you didn’t inherit that DNA from one single parent. That zigzag phenomenon.
  • Furthermore, triangulated DNA is only valid as far back as the closest common ancestor of any two of the three people.

Let’s explore some examples.

Building Triangulation Evidence – Ingredients and a Recipe

The strongest case of triangulation is when:

  • You and at least two additional cousins match on the same segment AND
  • Descend through different children of the common ancestral couple

Let’s look at a valid triangulated match.

In this first example, the magenta segment of DNA is at least partially shared by four of the six cousins and triangulates to their common great-grandfather. Let’s say that these cousins then match with two other people descended from different children of their great-great-great-grandparents on this same segment. Then the entire triangulation group will have confirmed that segment’s origin and push the descent of that segment back another two generations.

These people all coalesce into one line with their common great-grandparents.

I’m only showing 3 generations in this triangulated match, but the concept is the same no matter how many generations you reach back in time. Although, over time, segments inherited from any specific ancestor become smaller and smaller until they are no longer passed to the next generation.

In this pedigree chart, we’re only tracking the magenta DNA which is passed generation to generation in descendants.

Eventually, of course, those segments become smaller and indistinguishable as they either aren’t passed on at all or drop below vendor matching thresholds.

This chart shows the average amount of DNA you would carry from each generational ancestor. You inherit half of each parent’s DNA, but back further than that, you don’t receive exactly half of any ancestor’s DNA in any generation. Larger segments are generally cut in two and passed on partially, but smaller segments are often either passed on whole or not at all.

On average, you’ll carry 7 cM of your eight-times-great-grandparents. In reality, you may carry more or you may not carry any – and you are unlikely to carry the same segment as any random other descendants but we know it happens and you’ll find them if enough (or the right) descendants test.

Putting this another way, if you divide all of your approximate 7000 cM of DNA into 7 cM segments of equal length – you’ll have 1000 7 cM segments. So will every other descendant of your eight-times-great-grandparent. You can see how small the chances are of you both inheriting that same exact 7 cM segment through ten inheritance/transmission events, each. Yet it does happen.

I have several triangulated matches with descendants of Charles Dodson and his wife, Anne through multiple of their 9 (or so) children, ten generations back in my tree. Those triangulated matches range from 7-38 cM. It’s possible that those three largest matches at 38 cM could be related through multiple ancestors because we all have holes in our trees – including Anne’s surname.

Click to enlarge image

It helps immensely that Charles Dodson had several children who were quite prolific as well.

Of course, the further back in time, the more “proof” is necessary to eliminate other unknown common ancestors. This is exactly why matching through different children is important for triangulation and ancestor confirmation.

The method we use to confirm the common ancestor is that all of the descendants who match the tester on the same segment all also match each other. This greatly reduces the chances that these people are matching by chance. The more people in the triangulation group, the stronger the evidence. Of course, parental phasing or cross-matching, where available is an added confirmation bonus.

In our magenta inheritance example, we saw that three of the males and one of the females from three different descendants of the great-grandparents all carry at least a portion of that magenta segment of great-grandpa’s DNA.

Now, let’s take a look at a different scenario.

Why can’t siblings or close relatives be used as two of the three people needed for triangulation?

Aunts and Uncles

We know that the best way to determine if a match is valid is by parental phasing – your match also matching to one of your parents.

If both parents aren’t available, looking for close family matches in common with your match is the next hint that genealogists seek.

Let’s say that you and your match both match your aunt or uncle in common or their children.

You and your aunts or uncles matching DNA only pushes your common ancestor back to your grandparents.

At that point, your match is in essence matching to a segment that belongs to your grandparents. Your matches’ DNA, or your grandparents’ DNA could have randomly recombined and you and your aunt/cousins could be matching that third person by chance.

Ok, then, what about siblings?

Siblings

The most recent common ancestor (MRCA) of you and someone who also matches your sibling is your parents. Therefore, you and your sibling actually only count as one “person” in this scenario. In essence, it’s the DNA of your parent(s) that is matching that third person, so it’s not true triangulation. It’s the same situation as above with aunts/uncles, except the common ancestor is closer than your grandparents.

The DNA of your parents could have recombined in both siblings to look like a match to your match’s family. Or vice versa. Remember Parental Cross-Matching.

If you and a sibling inherited EXACTLY the same segment of your Mom’s and Dad’s DNA, and you match someone by chance – that person will match your sibling by chance as well.

In this example, you can see that both siblings 1 and 2 inherited the exact same segments of DNA at the same locations from both of their parents.

Of course, they also inherited segments at different locations that we’re not looking at that won’t match exactly between siblings, unless they are identical twins. But in this case, the inherited segments of both siblings will match someone whose DNA randomly combined with green or magenta dots in these positions to match a cross-section of both parents.

How False Positives Work and How to Avoid Them

We saw in our first example, displayed again above, what a valid triangulated match looks like. Now let’s expand this view and take a look more specifically at how false positive matches occur.

On the left-hand (blue) side of this graphic, we see four siblings that descend through their father from Great-grandpa who contributed that large magenta segment of DNA. That segment becomes reduced in descendants in subsequent generations.

In downstream generations, we can see gold, white and green segments being added to the DNA inherited by the four children from their ancestor’s spouses. Dad’s DNA is shown on the left side of each child, and Mom’s on the right.

  • Blue Children 1 and 2 inherited the same segments of DNA from Mom and Dad. Magenta from Dad and green from Mom.
  • Blue Child 3 inherited two magenta segments from Dad in positions 1 and 2 and one gold segment from Dad in position 3. They inherited all white segments from Mom.
  • Blue Child 4 inherited all gold segments from Dad and all white segments from Mom.

The family on the blue left-hand side is NOT related to the pink family shown at right. That’s important to remember.

I’ve intentionally constructed this graphic so that you can see several identical by chance (IBC) matches.

Child 5, the first pink sibling carries a white segment in position 1 from Dad and gold segments in positions 2 and 3 from Dad. From Mom, they inherited a green segment in position 1, magenta in position 2 and green in position 3.

IBC Match 1 – Looking at the blue siblings, we see that based on the DNA inherited from Pink Child 5’s parents, Pink Child 5 matches Blue Child 4 with white, gold and gold in positions 1-3, even though they weren’t inherited from the same parent in Blue Child 4. I circled this match in blue.

IBC Match 2 – Pink Child 5 also matches Blue Children 1 and 2 (red circles) because Pink Child 5 has green, magenta, and green in positions 1-3 and so do Blue Children 1 and 2. However, Blue Children 1 and 2 inherited the green and magenta segments from Mom and Dad respectively, not just from one parent.

Pink Child 5 matches Blue Children 1, 2 and 4, but not because they match by descent, but because their DNA zigzags back and forth between the blue children’s DNA contributed by both parents.

Therefore, while Pink Child 5 matches three of the Blue Children, they do not match either parent of the Blue Children.

IBC Match 3 – Pink Child 6 matches Blue Child 3 with white, magenta and gold in positions 1-3 based on the same colors of dots in those same positions found in Blue Child 3 – but inherited both paternally and maternally.

You can see that if we had the four parents available to test, that none of the Pink Children would match either the Blue Children’s mother or father and none of the Blue Children would match either of the Pink Children’s mother or father.

This is why we can’t use either siblings or close family relatives for triangulation.

Distant Cousins Are Best for Triangulation & Here’s Why

When triangulating with 3 people, the most recent common ancestor (MRCA) intersection of the closest two people is the place at which triangulation turns into only two lines being compared and ceases being triangulation. Triangle means 3.

If siblings are 2 of the 3 matching people, then their parents are essentially being compared to the third person.

If you, your aunt/uncle, and a third person match, your grandparents are the place in your tree where three lines converge into two.

The same holds true if you’re matching against a sibling pair on your match’s side, or a match and their aunt/uncle, etc.

The further back in your tree you can push that MRCA intersection, the more your triangulated match provides confirming evidence of a common ancestor and that the match is valid and not caused by random recombination.

That’s exactly what the descendants of Charles Dodson have been able to do through triangulation with multiple descendants from several of his children.

It’s also worth mentioning at this point that the reason autosomal DNA testing uses hundreds/thousands of base pairs in a comparison window and not 3 or 6 dots like in my example is that the probability of longer segments of DNA simply randomly matching by chance is reduced with length and SNP density which is the number of SNP locations tested within that cM range.

Hence a 7 cM/500 SNP minimum is the combined rule of thumb. At that level, roughly half of your matches will be valid and half will be identical by chance unless you’re dealing with endogamy. Then, raise your threshold accordingly.

Ok, So Where are We? A Triangulation Checklist for You!

I know this has been a relatively long educational article, but it’s important to really understand that testing close relatives is VERY important, but also why we can’t effectively use them for triangulation.

Here’s a handy-dandy summary matching/triangulation checklist for you to use as you work through your matches.

  • You inherit half of each of your parents’ DNA. There is no other place for you to obtain or inherit your DNA. There is no DNA fairy sprinkling you with DNA from another source:)
  • DNA does NOT skip generations, although in occasional rare circumstances, it may appear that this happened. In this situation, it’s incumbent upon you, the genealogist, to PROVE that an exception has occurred if you really believe it has. Those circumstances might be pedigree collapse or perhaps imputation. You’ll need to compare matches at vendors who provide a chromosome browser, triangulation, and full shared match list information. Never assume that you are the exception without hard and fast proof. We all know about assume, right?
  • Your siblings inherit half of your parents’ DNA too, but not the same exact half of your parent’s DNA that you other siblings did (unless they are identical twins.) You may inherit the exact same DNA from either or both of your parents on certain segments.
  • Your matches may match your parents on different or an additional segment that you did not inherit.
  • Every segment has an individual history. Evaluate every matching segment separately. One matching segment with someone could be maternal, one paternal, and one identical by chance.
  • You can confirm matches as valid if your match matches one of your parents, and you match one of your match’s parents. Parental Phasing is when your match matches your parent. Parental Cross-Matching is when you both match one of each other’s parents. To be complete, both people who match each other need to match one of the parents of the other person. This rule still holds even if you have a known common ancestor. I can’t even begin to tell you how many times I’ve been fooled.
  • 15-20% (or more with endogamy) of your matches will be identical by chance because either your DNA or your match’s DNA aligns in such a way that while they match you, they don’t match either of your parents.
  • Your siblings, aunts, and uncles will often inherit the same DNA as you – which means that identical by chance matches will also match them. That’s why we don’t use close family members for triangulation. We do utilize close family members to generate common match hints. (Remember the 20 cM shared match caveat at Ancestry)
  • While your siblings, aunts, and uncles are too close to use for triangulation, they are wonderful to identify ancestral matches. Some of their matches will match you as well, and some will not because your close family members inherited segments of your ancestor’s DNA that you did not. Everyone should test their oldest family members.
  • Triangulate your close family member’s matches separately from your own to shed more light on your ancestors.
  • Endogamy may interfere with parental phasing, meaning you may match because you and/or your match may have inherited some of the same DNA segment(s) from both sides of your tree and/or more DNA than might otherwise be expected.
  • Pedigree collapse needs to be considered when using parental phasing, especially when the same ancestor appears on both sides of your family tree. You may share more DNA with a match than expected.
  • Conversely, with pedigree collapse, your match may not match your parents, or vice versa, if a segment happens to have recombined in you in a way that drops the matching segments of your parents beneath the vendor’s match threshold.
  • While you will match all of your second cousins, you will only match approximately 90% of your third cousins and proportionally fewer as your relationship reaches further back in time.
  • Not being a DNA match with someone does NOT mean you’re NOT related to them, unless of course, you’re a second cousin (2C) or closer. It simply means you don’t carry any common ancestral segments above vendor thresholds.
  • At 2C or closer, if you’re not a DNA match, other alternative situations need to be considered – including the transfer/upload of the wrong person’s DNA file.
  • Imputation, a scientific process required of vendors may interfere with matching, especially in more distant relatives who have tested on different platforms.
  • Imputation artifacts will be less obvious when people are more closely related, meaning closer relatives can be expected to match on more and larger segments and imputation errors make less difference.
  • Imputation will not cause close relatives, meaning 2C or closer, to not match each other.
  • In addition to not supporting segment matching information, Ancestry down-weights some segments, removes some matching DNA, and does not show shared matches below 20cM, causing some people to misinterpret their lack of common matches in various ways.
  • To resolve questions about matching issues at Ancestry, testers can transfer/upload their DNA files to MyHeritage, FamilyTreeDNA, and GEDmatch and look for consistent matches on the same segment. Start and end locations may vary to some extent between vendors, but the segment size should be basically in the same location and roughly the same size.
  • GEDmatch does not use imputation but allows larger non-matching segments to combine as a single segment which sometimes causes extremely “generous” matches. GEDmatch matching is less reliable than FamilyTreeDNA or MyHeritage, but you can adjust the matching thresholds.
  • The best situation for matching is for both people to test at the same vendor who supports and provides segment data and a chromosome browser such as 23andMe, FamilyTreeDNA, or MyHeritage.
  • Siblings cannot be used for triangulation because the most recent common ancestor (MRCA) between you and your siblings is your parents. Therefore, the “three” people in the triangulation group is reduced to two lines immediately.
  • Uncles and aunts should not be used for triangulation because the most recent common ancestors between you and your aunts and uncles are your grandparents.
  • Conversely, you should not consider triangulating with siblings and close family members of your matches as proof of an ancestral relationship.
  • A triangulation group of 3 people is only confirmation as far back as when two of those people’s lines converge and reach a common ancestor.
  • Identical by chance (IBC) matching occurs when DNA from the maternal and paternal sides are mixed positionally in the child to resemble a maternal/paternal side match with someone else.
  • Identical by chance DNA admixture (when compared to a match) could have occurred in your parents or grandparent’s generation, or earlier, so the further back in time that people in a triangulation group reach, the more reliable the triangulation group is likely to be.
  • The larger the segments and/or the triangulation group, the stronger the evidence for a specific confirmed common ancestor.
  • Early families with a very large number of descendants may have many matching and triangulated members, even 9 or 10 generations later.
  • While exactly 50% of each ancestor’s DNA is not passed in each generation, on average, you will carry 7 cM of your ancestors 10 generations back in your tree. However, you may carry more, or none.
  • The percentage of matching descendants decreases with each generation beyond great-grandparents.
  • The ideal situation for triangulation is a significant number of people, greater than three, who match on the same reasonably sized segment (7 cM/500 SNP or larger) and descend from the same ancestor (or ancestral couple) through different children whose spouses in descendant generations are not also related.
  • This means that tree completion is an important factor in match/triangulation reliability.
  • Triangulating through different children of the ancestral couple makes it significantly less likely that a different unknown common ancestor is contributing that segment of DNA – like an unknown wife in a descendant generation.

Whew!!!

The Bottom Line

Here’s the bottom line.

  1. Don’t use close relatives to triangulate.
  2. Use parents for Parental Phasing.
  3. Use Parental Cross-Matching when possible.
  4. Use close relatives to look for shared common matches that may lead to triangulation possibilities.
  5. Triangulate your close relatives’ DNA in addition to your own for bonus genealogical information. They will match people that you don’t.
  6. For the most reliable triangulation results, use the most distant relatives possible, descended through different children of the common ancestral couple.
  7. Keep this checklist of best practices, cautions, and caveats handy and check the list as necessary when evaluating the strength of any match or triangulation group. It serves as a good reminder for what to check if something seems “off” or unusual.

Feel free to share and pass this article (and checklist) on to your genealogy buddies and matches as you explain triangulation and collaborate on your genealogy.

Have fun!!!

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Products and Services

Books

Genealogy Research

How to Download Your DNA Matching Segment Data and Why You Should

There are two or three types of data that testers may be able to download from DNA testing sites. Genealogy customers need to periodically download as much as possible.

  1. Raw data files needed for transferring DNA files from the company where you tested to other testing or analysis/comparison sites such as FamilyTreeDNA, MyHeritage, and GEDmatch for matching and other tools.
  2. Matching segment files which detail your matches, segment by segment with people whom you match.
  3. Match information files that provide you with additional information about your matches. What’s included varies by vendor.

This type of information is not uniformly available from all vendors, but is available as follows:

Vendor Raw Data File Matching Segment File Match Information File
FamilyTreeDNA Yes Yes Yes
MyHeritage Yes Yes Yes
23andMe Yes Yes Yes
Ancestry Yes No No
GedMatch Not a testing company, so no Yes Yes

I have provided step-by-step information about how to download your raw DNA data files and upload them to other vendors in a series of articles that you can find here.

Some of the answers in the table above need caveats because each vendor is different. Let’s take a look.

Matching Segment Files

In this article, I’ll provide information about how to download your matching segment and match information file(s).

Unfortunately, Ancestry does not provide any segment data at all, nor do they provide a way to download your match information. Third-party tools that did this for you have been banned by Ancestry, under threat of legal action, so this information is no longer available to Ancestry customers.

You can’t obtain this information from Ancestry, but you can transfer your DNA file to other vendors such as FamilyTreeDNA, MyHeritage and the third-party site, GEDmatch where you’ll receive additional matches. Some Ancestry matches will have transferred elsewhere as well, and you can take advantage of your matching segment information.

Why Do I Want a Matching Segment File?

The matching segment file provides you with information about exactly how and where you match each person.

Here’s an example that includes the match name, chromosome, start and end location of the match along with the total number of CentiMorgans (cM) and total SNPs in the matching segment. Your matching segment file consists of hundreds/thousands of rows of this information.

Determining who matches you on the same segment is important because it facilitates the identification of common ancestors. Segment matching is also the first step in triangulation which allows you to confirm descent from common ancestors with your matches.

I wrote about triangulation at each vendor in the following articles:

Matching and Triangulation help you sort out legitimate matches, and which ancestors that DNA segment comes from.

Sorting For Legitimate Matches

On each segment location of your DNA, you will match:

  • People from your Mom’s side
  • People from your Dad’s side
  • People that are identical by chance (IBC) where they match you because part of the DNA from your Mom’s side and part from your Dad’s side just happens to look like their DNA (or vice versa.)

You can see how matching works in this example of 10 DNA locations. You inherited half of your Mom’s DNA and half of your Dad’s.

  • Legitimate maternal matches to you on this segment will have all As in this location.
  • Legitimate paternal matches to you will have all Cs in this location.
  • Identical by chance matches will match you, because they have the same DNA as both of your parents that you carry – interspersed. They will not match either of your parents individually.

IBC matches DO technically match you, but accidentally. In other words, they are identical by chance (IBC) because they just happen to match the DNA of both of your parents intermixed. Conversely, you can match the DNA of their parents intermixed as well. Regardless of why, they are not a legitimate maternal or paternal match to you.

For example, you can see that the identical by chance (IBC) match to you, above, won’t match the legitimate maternal or legitimate paternal matches.

When comparing your matches on any segment, you’ll wind up with a group of people who match you and each other on your maternal side, a group on your paternal side, and “everyone else” who is IBC.

I wrote about IBD, identical by descent DNA and IBC, identical by chance DNA and how that works, here.

A downloadable segment match file allows you to sort all of your matches by chromosome and segment. That’s the first step in determining if your matches match each other – which is how to determine if people are legitimate matches or IBC.

Additionally, these files allow you to utilize features at DNAPainter along with the tools at DNAGedcom and Genetic Affairs.

Match Information File

There’s a second file you’ll want to download as well except at 23andMe who includes all of the information in one file. You’ll want to download these files from each vendor at the same time so they are coordinated and include the same matches from the same time.

Downloading the second file, your match information, provides additional information which will be helpful for your genealogy. The information in this file varies by vendor, but includes items such as, but not limited to:

  • Tree link
  • Haplogroup
  • Match date
  • Predicted Relationship Range
  • Actual Relationship
  • Total shared cM
  • Longest segment cM
  • Maternal or paternal bucket (FamilyTreeDNA)
  • Notes
  • Email
  • Family Surnames
  • Location
  • Percent of shared DNA

You never know when vendors are going to change something that will affect your matches, like 23andMe did last fall, so it’s a good idea to download periodically.

Downloading your segment match and match information files are free, so let’s do this.

Downloading Your Segment Match & Information Files

FamilyTreeDNA

Sign on to your account.

click images to enlarge

Under your Family Finder Autosomal DNA test results, click on Chromosome Browser.

On the chromosome browser page, at the top right, click on Download All Segments.

Caveat – if you access the chromosome browser through the Family Finder match page, shown below, you will receive the segment matches ONLY for the people you have selected.

After selecting specific matches, as shown above, the option on the chromosome browser page will only say “Download Segments.” It does NOT say “Download All Segments.”

Clicking on this link only downloads the segments that you match with those people, so always be sure to access “Download ALL Segments” directly through the chromosome browser selection on your Autosomal DNA Family Finder menu without going to your match page and selecting specific matches.

The segment download file includes only the segments, but not additional information, such as which side, maternal or paternal, those matches are bucketed to, surnames and so forth. You need to download a second file.

To download additional information about your matches, scroll to the very bottom of your Family Finder match page and click on either Download Matches or Download Filtered matches. If you’ve used a filter such as maternal or paternal, you’ll receive only those matches, so be sure no filters are in use to download all of your matches’ information.

Your reports will be downloaded to your computer, so save them someplace where you can find them.

MyHeritage

Sign in to your account and click on the DNA tab, then DNA Matches.

At the far right-hand side, you’ll see three little dots. Click on the dots and you’ll see the options to export both the entire DNA Matches list and the shared DNA segment info for all DNA Matches.

You’ll want to download both. The first file Is the DNA matches list.

To download your segment matches, select the second option, “Export shared DNA segment info…”

Your files will be emailed to you.

23andMe

At 23andMe, sign on to your account and click on “DNA Relatives” under the Ancestry tab.

You’ll see your list of matches. Scroll to the very bottom where you’ll see the link to “Download aggregate data.”

23andMe combines your segment and match information in one file.

Remember that at 23andMe, your matches are limited to 2000 (unless you’re a V5 subscriber), minus the number of people who have not opted in to Relative Sharing. Additionally, there will be a number of people in the download file whose names appear, but who don’t have any segment data. Those people opted-in to Relative Sharing, but not to share segment information.

For example, my download file has 2827 rows. Of those, 1769 are unique individuals, meaning that I have matches with multiple segments for 1058 people. This means that of my 2000 allowed matches, 231 (or more) did not opt-in for Relative Sharing. The “or more” means that 23andMe does not roll matches off the list if you have communicated with the person, so some people may actually have more than 2000 matches. It’s impossible to know how 23andMe approaches calculations in this case.

Of those 1769 unique individuals on my match list, 257, or 15% did not share segment information. I’d sure like for those to be automatically rolled off and replaced with the next 257 who do share. 1512 or roughly three-quarters, 75%, of my 2000 allowed matches are useful for genealogy.

Initially, when 23andMe made their changes last fall, they were reportedly limiting the download file number to 1000, but they have reversed that policy on the V3 and V4 chips. I downloaded files from both chip versions to confirm that’s true.

I don’t have the V5 chip subscription level, nor am I going to retest to do that, so I don’t know if V5 subscribers receive all 5000 of the allowed matches in their download file.

This is the perfect example of why it’s a good idea to download your match files periodically. 23andMe is the only testing vendor that restricts your matches and when they roll off your list, they are irretrievable.

Aside from that, safe is better than sorry. You never know when something will change at a vendor and you’ll wish you had downloaded your match files earlier.

GedMatch

GedMatch, a third-party vendor, provides lots of tools but isn’t intuitive and provides almost no tutorial or information about how to navigate or use their site. There are some YouTube videos and Kitty Cooper has written several how-to articles. GEDmatch has promised a facelift soon.

GEDmatch provides many tools for free, along with a Tier1 level which provides advanced features by subscription.

At GEDmatch, you can see up to 2000 matches for free, but you must be a Tier 1 subscription member to download your matches – and the download is restricted to your top 1000 matches.

There are two Tier 1 one-to-many comparison options that are very similar. For either, you’ll enter your kit number and make your selection. Given that you’re restricted to 1000 in the download, there is no reason to search for more than 1000 kits.

click to enlarge

Then, click on Visualization options

You will then see the list of visualization options which includes “List/CSV.”

Clicking on “List/CSV” provides you with options.

click to enlarge

You’ll want to select the Matched Segment List, and you can either select “Prevent Hard Breaks,” or not. Allowing hard breaks means that small non-matching regions between two matching segments is not ignored, and the two segments are reported as two separate segments – if they are large enough to be reported.

If you prevent hard breaks, non-matching regions of less than 500,000 thousand base positions are ignored, creating one larger blended segment. It’s my preference to allow hard breaks because I’ve seen too many instances of erroneously “blended” segments.

When your matching segment file is complete, you will be prompted to download to your computer.

Thanks to Genetic Affairs, I discovered an alternate way to obtain more than 1000 downloaded matches from GEDmatch.

GEDmatch Alternative Methodology

Genetic Affairs suggests using the DNA Segment Search with a minimum of 5000 kits, and to enable the option to “Prevent Hard Breaks.”

Do not close the session while GedMatch is processing or you’ll need to restart your query.

When finished click “Here” to download the file to your system.

Now you’re ready for part 2.

Next, you’ll want to select the Triangulation feature.

These functions take time, so you’ll be watching as the counter increases. Or maybe go eat dinner or research some genealogy.

I can hear the “Jeopardy countdown music

When finished, click on “Here” to download this second file.

Whew! Now you should have your segment and match information files from each company that supports this information and provides downloads.

Saving Files

I generally save my files by vendor and date. However, if you’re going to use the files for a special project – you may want to make a copy elsewhere. For example, I’m going to use these files for Genetic Affairs’ AutoSegment feature, so I’ve downloaded fresh files from each vendor on the same date and made a separate copy, stored in my Genetic Affairs folder. I’ll let you know how that goes😊

Bottom Line

  • Test at vendors that don’t accept transfers. Ancestry and 23andMe
  • Test at or transfer to the rest. FamilyTreeDNA, MyHeritage and GEDmatch
  • Unlock or subscribe to the advanced tools that include chromosome browsers, ethnicity, and more, depending on the vendor. FamilyTreeDNA, MyHeritage, GEDmatch
  • Upload or create trees at each vendor (except 23andMe who doesn’t support trees.)
  • Download as much information as you can from each vendor.
  • Work your matches through shared (in common with) matches, trees, segments, and clusters!

Have fun!!!

_____________________________________________________________

Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Products and Services

Books

Genealogy Research

Y DNA: Step-by-Step Big Y Analysis

Many males take the Big Y-700 test offered by FamilyTreeDNA, so named because testers receive the most granular haplogroup SNP results in addition to 700+ included STR marker results. If you’re not familiar with those terms, you might enjoy the article, STRs vs SNPs, Multiple DNA Personalities.

The Big Y test gives testers the best of both, along with contributing to the building of the Y phylotree. You can read about the additions to the Y tree via the Big Y, plus how it helped my own Estes project, here.

Some men order this test of their own volition, some at the request of a family member, and some in response to project administrators who are studying a specific topic – like a particular surname.

The Big Y-700 test is the most complete Y DNA test offered, testing millions of locations on the Y chromosome to reveal mutations, some unique and never before discovered, many of which are useful to genealogists. The Big Y-700 includes the traditional Y DNA STR marker testing along with SNP results that define haplogroups. Translated, both types of test results are compared to other men for genealogy, which is the primary goal of DNA testing.

Being a female, I often recruit males in my family surname lines and sponsor testing. My McNiel line, historic haplogroup R-M222, has been particularly frustrating both genealogically as well as genetically after hitting a brick wall in the 1700s. My McNeill cousin agreed to take a Big Y test, and this analysis walks through the process of understanding what those results are revealing.

After my McNeill cousin’s Big Y results came back from the lab, I spent a significant amount of time turning over every leaf to extract as much information as possible, both from the Big Y-700 DNA test itself and as part of a broader set of intertwined genetic information and genealogical evidence.

I invite you along on this journey as I explain the questions we hoped to answer and then evaluate Big Y DNA results along with other information to shed light on those quandaries.

I will warn you, this article is long because it’s a step-by-step instruction manual for you to follow when interpreting your own Big Y results. I’d suggest you simply read this article the first time to get a feel for the landscape, before working through the process with your own results. There’s so much available that most people leave laying on the table because they don’t understand how to extract the full potential of these test results.

If you’d like to read more about the Big Y-700 test, the FamilyTreeDNA white paper is here, and I wrote about the Big Y-700 when it was introduced, here.

You can read an overview of Y DNA, here, and Y DNA: The Dictionary of DNA, here.

Ok, get yourself a cuppa joe, settle in, and let’s go!

George and Thomas McNiel – Who Were They?

George and Thomas McNiel appear together in Spotsylvania County, Virginia records. Y DNA results, in combination with early records, suggest that these two men were brothers.

I wrote about discovering that Thomas McNeil’s descendant had taken a Y DNA test and matched George’s descendants, here, and about my ancestor George McNiel, here.

McNiel family history in Wilkes County, NC, recorded in a letter written in 1898 by George McNiel’s grandson tells us that George McNiel, born about 1720, came from Scotland with his two brothers, John and Thomas. Elsewhere, it was reported that the McNiel brothers sailed from Glasgow, Scotland and that George had been educated at the University of Edinburgh for the Presbyterian ministry but had a change of religious conviction during the voyage. As a result, a theological tiff developed that split the brothers.

George, eventually, if not immediately, became a Baptist preacher. His origins remain uncertain.

The brothers reportedly arrived about 1750 in Maryland, although I have no confirmation. By 1754, Thomas McNeil appeared in the Spotsylvania County, VA records with a male being apprenticed to him as a tailor. In 1757, in Spotsylvania County, the first record of George McNeil showed James Pey being apprenticed to learn the occupation of tailor.

If George and Thomas were indeed tailors, that’s not generally a country occupation and would imply that they both apprenticed as such when they were growing up, wherever that was.

Thomas McNeil is recorded in one Spotsylvania deed as being from King and Queen County, VA. If this is the case, and George and Thomas McNiel lived in King and Queen, at least for a time, this would explain the lack of early records, as King and Queen is a thrice-burned county. If there was a third brother, John, I find no record of him.

My now-deceased cousin, George McNiel, initially tested for the McNiel Y DNA and also functioned for decades as the family historian. George, along with his wife, inventoried the many cemeteries of Wilkes County, NC.

George believed through oral history that the family descended from the McNiel’s of Barra.

McNiel Big Y Kisumul

George had this lovely framed print of Kisimul Castle, seat of the McNiel Clan on the Isle of Barra, proudly displayed on his wall.

That myth was dispelled with the initial DNA testing when our line did not match the Barra line, as can be seen in the MacNeil DNA project, much to George’s disappointment. As George himself said, the McNiel history is both mysterious and contradictory. Amen to that, George!

McNiel Big Y Niall 9 Hostages

However, in place of that history, we were instead awarded the Niall of the 9 Hostages badge, created many years ago based on a 12 marker STR result profile. Additionally, the McNiel DNA was assigned to haplogroup R-M222. Of course, today’s that’s a far upstream haplogroup, but 15+ years ago, we had only a fraction of the testing or knowledge that we do today.

The name McNeil, McNiel, or however you spell it, resembles Niall, so on the surface, this made at least some sense. George was encouraged by the new information, even though he still grieved the loss of Kisimul Castle.

Of course, this also caused us to wonder about the story stating our line had originated in Scotland because Niall of the 9 Hostages lived in Ireland.

Niall of the 9 Hostages

Niall of the 9 Hostages was reportedly a High King of Ireland sometime between the 6th and 10th centuries. However, actual historical records place him living someplace in the mid-late 300s to early 400s, with his death reported in different sources as occurring before 382 and alternatively about 411. The Annals of the Four Masters dates his reign to 379-405, and Foras Feasa ar Eirinn says from 368-395. Activities of his sons are reported between 379 and 405.

In other words, Niall lived in Ireland about 1500-1600 years ago, give or take.

Migration

Generally, migration was primarily from Scotland to Ireland, not the reverse, at least as far as we know in recorded history. Many Scottish families settled in the Ulster Plantation beginning in 1606 in what is now Northern Ireland. The Scots-Irish immigration to the states had begun by 1718. Many Protestant Scottish families immigrated from Ireland carrying the traditional “Mc” names and Presbyterian religion, clearly indicating their Scottish heritage. The Irish were traditionally Catholic. George could have been one of these immigrants.

We have unresolved conflicts between the following pieces of McNeil history:

  • Descended from McNeil’s of Barra – disproved through original Y DNA testing.
  • Immigrated from Glasgow, Scotland, and schooled in the Presbyterian religion in Edinburgh.
  • Descended from the Ui Neill dynasty, an Irish royal family dominating the northern half of Ireland from the 6th to 10th centuries.

Of course, it’s possible that our McNiel/McNeil line could have been descended from the Ui Neill dynasty AND also lived in Scotland before immigrating.

It’s also possible that they immigrated from Ireland, not Scotland.

And finally, it’s possible that the McNeil surname and M222 descent are not related and those two things are independent and happenstance.

A New Y DNA Tester

Since cousin George is, sadly, deceased, we needed a new male Y DNA tester to represent our McNiel line. Fortunately, one such cousin graciously agreed to take the Big Y-700 test so that we might, hopefully, answer numerous questions:

  • Does the McNiel line have a unique haplogroup, and if so, what does it tell us?
  • Does our McNiel line descend from Ireland or Scotland?
  • Where are our closest geographic clusters?
  • What can we tell by tracing our haplogroup back in time?
  • Do any other men match the McNiel haplogroup, and what do we know about their history?
  • Does the Y DNA align with any specific clans, clan history, or prehistory contributing to clans?

With DNA, you don’t know what you don’t know until you test.

Welcome – New Haplogroup

I was excited to see my McNeill cousin’s results arrive. He had graciously allowed me access, so I eagerly took a look.

He had been assigned to haplogroup R-BY18350.

McNiel Big Y branch

Initially, I saw that indeed, six men matched my McNeill cousin, assigned to the same haplogroup. Those surnames were:

  • Scott
  • McCollum
  • Glass
  • McMichael
  • Murphy
  • Campbell

Notice that I said, “were.” That’s right, because shortly after the results were returned, based on markers called private variants, Family Tree DNA assigned a new haplogroup to my McNeill cousin.

Drum roll please!!!

Haplogroup R-BY18332

McNiel Big Y BY18332

Additionally, my cousin’s Big Y test resulted in several branches being split, shown on the Block Tree below.

McNIel Big Y block tree

How cool is this!

This Block Tree graphic shows, visually, that our McNiel line is closest to McCollum and Campbell testers, and is a brother clade to those branches showing to the left and right of our new R-BY18332. It’s worth noting that BY25938 is an equivalent SNP to BY18332, at least today. In the future, perhaps another tester will test, allowing those two branches to be further subdivided.

Furthermore, after the new branches were added, Cousin McNeill has no more Private Variants, which are unnamed SNPs. There were all utilized in naming additional tree branches!

I wrote about the Big Y Block Tree here.

Niall (Or Whoever) Was Prolific

The first thing that became immediately obvious was how successful our progenitor was.

McNiel Big Y M222 project

click to enlarge

In the MacNeil DNA project, 38 men with various surname spellings descend from M222. There are more in the database who haven’t joined the MacNeil project.

Whoever originally carried SNP R-M222, someplace between 2400 and 5900 years ago, according to the block tree, either had many sons who had sons, or his descendants did. One thing is for sure, his line certainly is in no jeopardy of dying out today.

The Haplogroup R-M222 DNA Project, which studies this particular haplogroup, reads like a who’s who of Irish surnames.

Big Y Match Results

Big Y matches must have no more than 30 SNP differences total, including private variants and named SNPs combined. Named SNPs function as haplogroup names. In other words, Cousin McNeill’s terminal SNP, meaning the SNP furthest down on the tree, R-BY18332, is also his haplogroup name.

Private variants are mutations that have occurred in the line being tested, but not yet in other lines. Occurrences of private variants in multiple testers allow the Private Variant to be named and placed on the haplotree.

Of course, Family Tree DNA offers two types of Y DNA testing, STR testing which is the traditional 12, 25, 37, 67 and 111 marker testing panels, and the Big Y-700 test which provides testers with:

  • All 111 STR markers used for matching and comparison
  • Another 589+ STR markers only available through the Big Y test increasing the total STR markers tested from 111 to minimally 700
  • A scan of the Y chromosome, looking for new and known SNPs and STR mutations

Of course, these tests keep on giving, both with matching and in the case of the Big Y – continued haplogroup discovery and refinement in the future as more testers test. The Big Y is an investment as a test that keeps on giving, not just a one-time purchase.

I wrote about the Big Y-700 when it was introduced here and a bit later here.

Let’s see what the results tell us. We’ll start by taking a look at the matches, the first place that most testers begin.

Mcniel Big Y STR menu

Regular Y DNA STR matching shows the results for the STR results through 111 markers. The Big Y section, below, provides results for the Big Y SNPs, Big Y matches and additional STR results above 111 markers.

McNiel Big Y menu

Let’s take a look.

STR and SNP Testing

Of Cousin McNeil’s matches, 2 Big Y testers and several STR testers carry some variant of the Neal, Neel, McNiel, McNeil, O’Neil, etc. surnames by many spellings.

While STR matching is focused primarily on a genealogical timeframe, meaning current to roughly 500-800 years in the past, SNP testing reaches much further back in time.

  • STR matching reaches approximately 500-800 years.
  • Big Y matching reaches approximately 1500 years.
  • SNPs and haplogroups reach back infinitely, and can be tracked historically beyond the genealogical timeframe, shedding light on our ancestors’ migration paths, helping to answer the age-old question of “where did we come from.”

These STR and Big Y time estimates are based on a maximum number of mutations for testers to be considered matches paired with known genealogy.

Big Y results consider two men a match if they have 30 or fewer total SNP differences. Using NGS (next generation sequencing) scan technology, the targeted regions of the Y chromosome are scanned multiple times, although not all regions are equally useful.

Individually tested SNPs are still occasionally available in some cases, but individual SNP testing has generally been eclipsed by the greatly more efficient enriched technology utilized with Big Y testing.

Think of SNP testing as walking up to a specific location and taking a look, while NGS scan technology is a drone flying over the entire region 30-50 times looking multiple times to be sure they see the more distant target accurately.

Multiple scans acquiring the same read in the same location, shown below in the Big Y browser tool by the pink mutations at the red arrow, confirm that NGS sequencing is quite reliable.

McNiel Big Y browser

These two types of tests, STR panels 12-111 and the SNP-based Big Y, are meant to be utilized in combination with each other.

STR markers tend to mutate faster and are less reliable, experiencing frustrating back mutations. SNPs very rarely experience this level of instability. Some regions of the Y chromosome are messier or more complicated than others, causing problems with interpreting reads reliably.

For purposes of clarity, the string of pink A reads above is “not messy,” and “A” is very clearly a mutation because all ~39 scanned reads report the same value of “A,” and according to the legend, all of those scans are high quality. Multiple combined reads of A and G, for example, in the same location, would be tough to call accurately and would be considered unreliable.

You can see examples of a few scattered pink misreads, above.

The two different kinds of tests produce results for overlapping timeframes – with STR mutations generally sifting through closer relationships and SNPs reaching back further in time.

Many more men have taken the Y DNA STR tests over the last 20 years. The Big Y tests have only been available for the past handful of years.

STR testing produces the following matches for my McNiel cousin:

STR Level STR Matches STR Matches Who Took the Big Y % STR Who Took Big Y STR Matches Who Also Match on the Big Y
12 5988 796 13 52
25 6660 725 11 57
37 878 94 11 12
67 1225 252 21 23
111 4 2 50 1

Typically, one would expect that all STR matches that took the Big Y would match on the Big Y, since STR results suggest relationships closer in time, but that’s not the case.

  • Many STR testers who have taken the Big Y seem to be just slightly too distant to be considered a Big Y match using SNPs, which flies in the face of conventional wisdom.
  • However, this could easily be a function of the fact that STRs mutate both backward and forwards and may have simply “happened” to have mutated to a common value – which suggests a closer relationship than actually exists.
  • It could also be that the SNP matching threshold needs to be raised since the enhanced and enriched Big Y-700 technology now finds more mutations than the older Big Y-500. I would like to see SNP matching expanded to 40 from 30 because it seems that clan connections may be being missed. Thirty may have been a great threshold before the more sensitive Big Y-700 test revealed more mutations, which means that people hit that 30 threshold before they did with previous tests.
  • Between the combination of STRs and SNPs mutating at the same time, some Big Y matches are pushed just out of range.

In a nutshell, the correlation I expected to find in terms of matching between STR and Big Y testing is not what I found. Let’s take a look at what we discovered.

It’s worth noting that the analysis is easier if you are working together with at least your closest matches or have access via projects to at least some of their results. You can see common STR values to 111 in projects, such as surname projects. Project administrators can view more if project members have allowed access.

Unexpected Discoveries and Gotchas

While I did expect STR matches to also match on the Big Y, I don’t expect the Big Y matches to necessarily match on the STR tests. After all, the Big Y is testing for more deep-rooted history.

Only one of the McNiel Big Y matches also matches at all levels of STR testing. That’s not surprising since Big Y matching reaches further back in time than STR testing, and indeed, not all STR testers have taken a Big Y test.

Of my McNeill cousin’s closest Big Y matches, we find the following relative to STR matching.

Surname Ancestral Location Big Y Variant/SNP Difference STR Match Level
Scott 1565 in Buccleuch, Selkirkshire, Scotland 20 12, 25, 37, 67
McCollum Not listed 21 67 only
Glass 1618 in Banbridge, County Down, Ireland 23 12, 25, 67
McMichael 1720 County Antrim, Ireland 28 67 only
Murphy Not listed 29 12, 25, 37, 67
Campbell Scotland 30 12, 25, 37, 67, 111

It’s ironic that the man who matches on all STR levels has the most variants, 30 – so many that with 1 more, he would not have been considered a Big Y match at all.

Only the Campbell man matches on all STR panels. Unfortunately, this Campbell male does not match the Clan Campbell line, so that momentary clan connection theory is immediately put to rest.

Block Tree Matches – What They Do, and Don’t, Mean

Note that a Carnes male, the other person who matches my McNeill cousin at 111 STR markers and has taken a Big Y test does not match at the Big Y level. His haplogroup BY69003 is located several branches up the tree, with our common ancestor, R-S588, having lived about 2000 years ago. Interestingly, we do match other R-S588 men.

This is an example where the total number of SNP mutations is greater than 30 for these 2 men (McNeill and Carnes), but not for my McNeill cousin compared with other men on the same S588 branch.

McNiel Big Y BY69003

By searching for Carnes on the block tree, I can view my cousin’s match to Mr. Carnes, even though they don’t match on the Big Y. STR matches who have taken the Big Y test, even if they don’t match at the Big Y level, are shown on the Block Tree on their branch.

By clicking on the haplogroup name, R-BY69003, above, I can then see three categories of information about the matches at that haplogroup level, below.

McNiel Big Y STR differences

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By selecting “Matches,” I can see results under the column, “Big Y.” This does NOT mean that the tester matches either Mr. Carnes or Mr. Riker on the Big Y, but is telling me that there are 14 differences out of 615 STR markers above 111 markers for Mr. Carnes, and 8 of 389 for Mr. Riker.

In other words, this Big Y column is providing STR information, not indicating a Big Y match. You can’t tell one way or another if someone shown on the Block Tree is shown there because they are a Big Y match or because they are an STR match that shares the same haplogroup.

As a cautionary note, your STR matches that have taken the Big Y ARE shown on the block tree, which is a good thing. Just don’t assume that means they are Big Y matches.

The 30 SNP threshold precludes some matches.

My research indicates that the people who match on STRs and carry the same haplogroup, but don’t match at the Big Y level, are every bit as relevant as those who do match on the Big Y.

McNIel Big Y block tree menu

If you’re not vigilant when viewing the block tree, you’ll make the assumption that you match all of the people showing on the Block Tree on the Big Y test since Block Tree appears under the Big Y tools. You have to check Big Y matches specifically to see if you match people shown on the Block Tree. You don’t necessarily match all of them on the Big Y test, and vice versa, of course.

You match Block Tree inhabitants either:

  • On the Big Y, but not the STR panels
  • On the Big Y AND at least one level of STRs between 12 and 111, inclusive
  • On STRs to someone who has taken the Big Y test, but whom you do not match on the Big Y test

Big Y-500 or Big Y-700?

McNiel Big Y STR differences

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Looking at the number of STR markers on the matches page of the Block Tree for BY69003, above, or on the STR Matches page is the only way to determine whether or not your match took the Big Y-700 or the Big Y-500 test.

If you add 111 to the Big Y SNP number of 615 for Mr. Carnes, the total equals 726, which is more than 700, so you know he took the Big Y-700.

If you add 111 to 389 for Mr. Riker, you get 500, which is less than 700, so you know that he took the Big Y-500 and not the Big Y-700.

There are still a very small number of men in the database who did not upgrade to 111 when they ordered their original Big Y test, but generally, this calculation methodology will work. Today, all Big Y tests are upgraded to 111 markers if they have not already tested at that level.

Why does Big Y-500 vs Big Y-700 matter? The enriched chemistry behind the testing technology improved significantly with the Big Y-700 test, enhancing Y-DNA results. I was an avowed skeptic until I saw the results myself after upgrading men in the Estes DNA project. In other words, if Big Y-500 testers upgrade, they will probably have more SNPs in common.

You may want to contact your closest Big Y-500 matches and ask if they will consider upgrading to the Big Y-700 test. For example, if we had close McNiel or similar surname matches, I would do exactly that.

Matching Both the Big Y and STRs – No Single Source

There is no single place or option to view whether or not you match someone BOTH on the Big Y AND STR markers. You can see both match categories individually, of course, but not together.

You can determine if your STR matches took the Big Y, below, and their haplogroup, which is quite useful, but you can’t tell if you match them at the Big Y level on this page.

McNiel Big Y STR match Big Y

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Selecting “Display Only Matches With Big Y” means displaying matches to men who took the Big Y test, not necessarily men you match on the Big Y. Mr. Conley, in the example above, does not match my McNeill cousin on the Big Y but does match him at 12 and 25 STR markers.

I hope FTDNA will add three display options:

  • Select only men that match on the Big Y in the STR panel
  • Add an option for Big Y on the advanced matches page
  • Indicate men who also match on STRs on the Big Y match page

It was cumbersome and frustrating to have to view all of the matches multiple times to compile various pieces of information in a separate spreadsheet.

No Big Y Match Download

There is also no option to download your Big Y matches. With a few matches, this doesn’t matter, but with 119 matches, or more, it does. As more people test, everyone will have more matches. That’s what we all want!

What you can do, however, is to download your STR matches from your match page at levels 12-111 individually, then combine them into one spreadsheet. (It would be nice to be able to download them all at once.)

McNiel Big Y csv

You can then add your Big Y matches manually to the STR spreadsheet, or you can simply create a separate Big Y spreadsheet. That’s what I chose to do after downloading my cousin’s 14,737 rows of STR matches. I told you that R-M222 was prolific! I wasn’t kidding.

This high number of STR matches also perfectly illustrates why the Big Y SNP results were so critical in establishing the backbone relationship structure. Using the two tools together is indispensable.

An additional benefit to downloading STR results is that you can sort the STR spreadsheet columns in surname order. This facilitates easily spotting all spelling variations of McNiel, including words like Niel, Neal and such that might be relevant but that you might not notice otherwise.

Creating a Big Y Spreadsheet

My McNiel cousin has 119 Big Y-700 matches.

I built a spreadsheet with the following columns facilitating sorting in a number of ways, with definitions as follows:

McNiel Big Y spreadsheet

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  • First Name
  • Last Name – You will want to search matches on your personal page at Family Tree DNA by this surname later, so be sure if there is a hyphenated name to enter it completely.
  • Haplogroup – You’ll want to sort by this field.
  • Convergent – A field you’ll complete when doing your analysis. Convergence is the common haplogroup in the tree shared by you and your match. In the case of the green matches above, which are color-coded on my spreadsheet to indicate the closest matches with my McNiel cousin, the convergent haplogroup is BY18350.
  • Common Tree Gen – This column is the generations on the Block Tree shown to this common haplogroup. In the example above, it’s between 9 and 14 SNP generations. I’ll show you where to gather this information.
  • Geographic Location – Can be garnered from 4 sources. No color in that cell indicates that this information came from the Earliest Known Ancestor (EKA) field in the STR matches. Blue indicates that I opened the tree and pulled the location information from that source. Orange means that someone else by the same surname whom the tester also Y DNA matches shows this location. I am very cautious when assigning orange, and it’s risky because it may not be accurate. A fourth source is to use Ancestry, MyHeritage, or another genealogical resource to identify a location if an individual provides genealogical information but no location in the EKA field. Utilizing genealogy databases is only possible if enough information is provided to make a unique identification. John Smith 1700-1750 won’t do it, but Seamus McDougal (1750-1810) married to Nelly Anderson might just work.
  • STR Match – Tells me if the Big Y match also matches on STR markers, and if so, which ones. Only the first 111 markers are used for matching. No STR match generally means the match is further back in time, but there are no hard and fast rules.
  • Big Y Match – My original goal was to combine this information with the STR match spreadsheet. If you don’t wish to combine the two, then you don’t need this column.
  • Tree – An easy way for me to keep track of which matches do and do not have a tree. Please upload or create a tree.

You can also add a spreadsheet column for comments or contact information.

McNiel Big Y profile

You will also want to click your match’s name to display their profile card, paying particular attention to the “About Me” information where people sometimes enter genealogical information. Also, scan the Ancestral Surnames where the match may enter a location for a specific surname.

Private Variants

I added additional spreadsheet columns, not shown above, for Private Variant analysis. That level of analysis is beyond what most people are interested in doing, so I’m only briefly discussing this aspect. You may want to read along, so you at least understand what you are looking at.

Clicking on Private Variants in your Big Y Results shows your variants, or mutations, that are unnamed as SNPs. When they are named, they become SNPs and are placed on the haplotree.

The reference or “normal” state for the DNA allele at that location is shown as the “Reference,” and “Genotype” is the result of the tester. Reference results are not shown for each tester, because the majority are the same. Only mutations are shown.

McNiel Big Y private variants

There are 5 Private Variants, total, for my cousin. I’ve obscured the actual variant numbers and instead typed in 111111 and 222222 for the first two as examples.

McNiel Big Y nonmatching variants

In our example, there are 6 Big Y matches, with matches one and five having the non-matching variants shown above.

Non-matching variants mean that the match, Mr. Scott, in example 1, does NOT match the tester (my cousin) on those variants.

  • If the tester (you) has no mutation, you won’t have a Private Variant shown on your Private Variant page.
  • If the tester does have a Private Variant shown, and that variant shows ON their matches list of non-matching variants, it means the match does NOT match the tester, and either has the normal reference value or a different mutation. Explained another way, if you have a mutation, and that variant is listed on your match list of Non-Matching Variants, your match does NOT match you and does NOT have the same mutation.
  • If the match does NOT have the Private Variant on their list, that means the match DOES match the tester, and they both have the same mutation, making this Private Variant a candidate to be named as a new SNP.
  • If you don’t have a Private Variant listed, but it shows in the Non-Matching Variants of your match, that means you have the reference or normal value, and they have a mutation.

In example #1, above, the tester has a mutation at variant 111111, and 111111 is shown as a Non-Matching Variant to Mr. Scott, so Mr. Scott does NOT match the tester. Mr. Scott also does NOT match the tester at locations 222222 and 444444.

In example #5, 111111 is NOT shown on the Non-Matching Variant list, so Mr. Treacy DOES match the tester.

I have a terrible time wrapping my head around the double negatives, so it’s critical that I make charts.

On the chart below, I’ve listed the tester’s private variants in an individual column each, so 111111, 222222, etc.

For each match, I’ve copy and pasted their Non-Matching Variants in a column to the right of the tester’s variants, in the lavender region. In this example, I’ve typed the example variants into separate columns for each tester so you can see the difference. Remember, a non-matching variant means they do NOT match the tester’s mutation.

McNiel private variants spreadsheet

On my normal spreadsheet where the non-matching variants don’t have individuals columns, I then search for the first variant, 111111. If the variant does appear in the list, it means that match #1 does NOT have the mutation, so I DON’T put an X in the box for match #1 under 111111.

In the example above, the only match that does NOT have 111111 on their list of Non-Matching Variants is #5, so an X IS placed in that corresponding cell. I’ve highlighted that column in yellow to indicate this is a candidate for a new SNP.

You can see that no one else has the variant, 222222, so it truly is totally private. It’s not highlighted in yellow because it’s not a candidate to be a new SNP.

Everyone shares mutation 333333, so it’s a great candidate to become a new SNP, as is 555555.

Match #6 shares the mutation at 444444, but no one else does.

This is a manual illustration of an automated process that occurs at Family Tree DNA. After Big Y matches are returned, automated software creates private variant lists of potential new haplogroups that are then reviewed internally where SNPs are evaluated, named, and placed on the tree if appropriate.

If you follow this process and discover matches, you probably don’t need to do anything, as the automated review process will likely catch up within a few days to weeks.

Big Y Matches

In the case of the McNiel line, it was exciting to discover several private variants, mutations that were not yet named SNPs, found in several matches that were candidates to be named as SNPs and placed on the Y haplotree.

Sure enough, a few days later, my McNeill cousin had a new haplogroup assignment.

Most people have at least one Private Variant, locations in which they do NOT match another tester. When several people have these same mutations, and they are high-quality reads, the Private Variant qualifies to be added to the haplotree as a SNP, a task performed at FamilyTreeDNA by Michael Sager.

If you ever have the opportunity to hear Michael speak, please do so. You can watch Michael’s presentation at Genetic Genealogy Ireland (GGI) titled “The Tree of Mankind,” on YouTube, here, compliments of Maurice Gleeson who coordinates GGI. Maurice has also written about the Gleeson Y DNA project analysis, here.

As a result of Cousin McNeill’s test, six new SNPs have been added to the Y haplotree, the tree of mankind. You can see our new haplogroup for our branch, BY18332, with an equivalent SNP, BY25938, along with three sibling branches to the left and right on the tree.

McNiel Big Y block tree 4 branch

Big Y testing not only answers genealogical questions, it advances science by building out the tree of mankind too.

The surname of the men who share the same haplogroup, R-BY18332, meaning the named SNP furthest down the tree, are McCollum and Campbell. Not what I expected. I expected to find a McNeil who does match on at least some STR markers. This is exactly why the Big Y is so critical to define the tree structure, then use STR matches to flesh it out.

Taking the Big Y-700 test provided granularity between 6 matches, shown above, who were all initially assigned to the same branch of the tree, BY18350, but were subsequently divided into 4 separate branches. My McNiel cousin is no longer equally as distant from all 6 men. We now know that our McNiel line is genetically closer on the Y chromosome to Campbell and McCollum and further distant from Murphy, Scott, McMichael, and Glass.

Not All SNP Matches are STR Matches

Not all SNP matches are also STR matches. Some relationships are too far back in time. However, in this case, while each person on the BY18350 branches matches at some STR level, only the Campbell individual matches at all STR levels.

Remember that variants (mutations) are accumulating down both respective branches of the tree at the same time, meaning one per roughly every 100 years (if 100 is the average number we want to use) for both testers. A total of 30 variants or mutations difference, an average of 15 on each branch of the tree (McNiel and their match) would suggest a common ancestor about 1500 years ago, so each Big Y match should have a common ancestor 1500 years ago or closer. At least on average, in theory.

The Big Y test match threshold is 30 variants, so if there were any more mismatches with the Campbell male, they would not have been a Big Y match, even though they have the exact same haplogroup.

Having the same haplogroup means that their terminal SNP is identical, the SNP furthest down the tree today, at least until someone matches one of them on their Private Variants (if any remain unnamed) and a new terminal SNP is assigned to one or both of them.

Mutations, and when they happen, are truly a roll of the dice. This is why viewing all of your Big Y Block Tree matches is critical, even if they don’t show on your Big Y match list. One more variant and Campbell would have not been shown as a match, yet he is actually quite close, on the same branch, and matches on all STR panels as well.

SNPs Establish the Backbone Structure

I always view the block tree first to provide a branching tree structure, then incorporate STR matches into the equation. Both can equally as important to genealogy, but haplogroup assignment is the most accurate tool, regardless of whether the two individuals match on the Big Y test, especially if the haplogroups are relatively close.

Let’s work with the Block Tree.

The Block Tree

McNIel Big Y block tree menu

Clicking on the link to the Block Tree in the Big Y results immediately displays the tester’s branch on the tree, below.

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On the left side are SNP generation markers. Keep in mind that approximate SNP generations are marked every 5 generations. The most recent generations are based on the number of private variants that have not yet been assigned as branches on the tree. It’s possible that when they are assigned that they will be placed upstream someplace, meaning that placement will reduce the number of early branches and perhaps increase the number of older branches.

The common haplogroup of all of the branches shown here with the upper red arrow is R-BY3344, about 15 SNP generations ago. If you’re using 100 years per SNP generation, that’s about 1500 years. If you’re using 80 years, then 1200 years ago. Some people use even fewer years for calculations.

If some of the private variants in the closer branches disappear, then the common ancestral branch may shift to closer in time.

This tree will always be approximate because some branches can never be detected. They have disappeared entirely over time when no males exist to reproduce.

Conversely, subclades have been born since a common ancestor clade whose descendants haven’t yet tested. As more people test, more clades will be discovered.

Therefore, most recent common ancestor (MRCA) haplogroup ages can only be estimated, based on who has tested and what we know today. The tree branches also vary depending on whether testers have taken the Big Y-500 or the more sensitive Big Y-700, which detects more variants. The Y haplotree is a combination of both.

Big Y-500 results will not be as granular and potentially do not position test-takers as far down the tree as Big Y-700 results would if they upgraded. You’ll need to factor that into your analysis if you’re drawing genealogical conclusions based on these results, especially close results.

You’ll note that the direct path of descent is shown above with arrows from BY3344 through the first blue box with 5 equivalent SNPS, to the next white box, our branch, with two equivalent SNPs. Our McNeil ancestor, the McCollum tester, and the Campell tester have no unresolved private variants between them, which suggests they are probably closer in time than 10 generations back. You can see that the SNP generations are pushed “up” by the neighbor variants.

Because of the fact that private variants don’t occur on a clock cycle and occur in individual lines at an unsteady rate, we must use averages.

That means that when we look further “up” the tree, clicking generation by generation on the up arrow above BY3344, the SNP generations on the left side “adjust” based on what is beneath, and unseen at that level.

The Block Tree Adjusts

Note, in the example above, BY3344 is at SNP generation 15.

Next, I clicked one generation upstream, to R-S668.

McNiel Big Y block tree S668

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You can see that S668 is about 21 SNP generations upstream, and now BY3344 is listed as 20 generations, not 15. You can see our branch, BY3344, but you can no longer see subclades or our matches below that branch in this view.

You can, however, see two matches that descend through S668, brother branches to BY3344, red arrows at far right.

Clicking on the up arrow one more time shows us haplogroup S673, below, and the child branches. The three child branches on which the tester has matches are shown with red arrows.

McNiel Big Y S673

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You’ll immediately notice that now S668 is shown at 19 SNP generations, not 20, and S673 is shown at 20. This SNP generation difference between views is a function of dealing with aggregated and averaged private variants on combined lines and causes the SNP generations to shift. This is also why I always say “about.”

As you continue to click up the tree, the shifting SNP generations continue, reminding us that we can’t truly see back in time. We can only achieve approximations, but those approximations improve as more people test, and more SNPs are named and placed in their proper places on the phylotree.

I love the Block Tree, although I wish I could see further side-to-side, allowing me to view all of the matches on one expanded tree so I can easily see their relationships to the tester, and each other.

Countries and Origins

In addition to displaying shared averaged autosomal origins of testers on a particular branch, if they have taken the Family Finder test and opted-in to sharing origins (ethnicity) results, you can also view the countries indicated by testers on that branch along with downstream branches of the tree.

McNiel Big Y countries

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For example, the Countries tab for S673 is shown above. I can see matches on this branch with no downstream haplogroup currently assigned, as well as cumulative results from downstream branches.

Still, I need to be able to view this information in a more linear format.

The Block Tree and spreadsheet information beautifully augment the haplotree, so let’s take a look.

The Haplotree

On your Y DNA results page, click on the “Haplotree and SNPs” link.

McNIel Big Y haplotree menu

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The Y haplotree will be displayed in pedigree style, quite familiar to genealogists. The SNP legend will be shown at the top of the display. In some cases, “presumed positive” results occur where coverage is lacking, back mutations or read errors are encountered. Presumed positive is based on positive SNPs further down the tree. In other words, that yellow SNP below must read positive or downstream ones wouldn’t.

McNIel Big Y pedigree descent

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The tester’s branch is shown with the grey bar. To the right of the haplogroup-defining SNP are listed the branch and equivalent SNP names. At far right, we see the total equivalent SNPs along with three dots that display the Country Report. I wish the haplotree also showed my matches, or at least my matching surnames, allowing me to click through. It doesn’t, so I have to return to the Big Y page or STR Matches page, or both.

I’ve starred each branch through which my McNiell cousin descends. Sibling branches are shown in grey. As you’ll recall from the Block Tree, we do have matches on those sibling branches, shown side by side with our branch.

The small numbers to the right of the haplogroup names indicate the number of downstream branches. BY18350 has three, all displayed. But looking upstream a bit, we see that DF97 has 135 downstream branches. We also have matches on several of those branches. To show those branches, simply click on the haplogroup.

The challenge for me, with 119 McNeill matches, is that I want to see a combination of the block tree, my spreadsheet information, and the haplotree. The block tree shows the names, my spreadsheet tells me on which branches to look for those matches. Many aren’t easily visible on the block tree because they are downstream on sibling branches.

Here’s where you can find and view different pieces of information.

Data and Sources STR Matches Page Big Y Matches Page Block Tree Haplogroups & SNPs Page
STR matches Yes No, but would like to see who matches at which STR levels If they have taken Big Y test, but doesn’t mean they match on Big Y matching No
SNP matches *1 Shows if STR match has common haplogroup, but not if tester matches on Big Y No, but would like to see who matches at which STR level Big Y matches and STR matches that aren’t Big Y matches are both shown No, but need this feature – see combined haplotree/ block tree
Other Haplogroup Branch Residents Yes, both estimated and tested No, use block tree or click through to profile card, would like to see haplogroup listed for Big Y matches Yes, both Big Y and STR tested, not estimated. Cannot tell if person is Big Y match or STR match, or both. No individuals, but would like that as part of countries report, see combined haplotree/block tree
Fully Expanded Phylotree No No Would like ability to see all branches with whom any Big Y or STR match resides at one time, even if it requires scrolling Yes, but no match information. Matches report could be added like on Block Tree.
Averaged Ethnicities if Have FF Test No No Yes, by haplogroup branch No
Countries Matches map STR only No, need Big Y matches map Yes Yes
Earliest Known Ancestor Yes No, but can click through to profile card No No
Customer Trees Yes No, need this link No No
Profile Card Yes, click through Yes, click through Yes, click through No match info on this page
Downloadable data By STR panel only, would like complete download with 1 click, also if Big Y or FF match Not available at all No No
Path to common haplogroup No No, but would like to see matches haplogroup and convergent haplogroup displayed No, would like the path to convergent haplogroup displayed as an option No, see combined match-block -haplotree in next section

*1 – the best way to see the haplogroup of a Big Y match is to click on their name to view their profile card since haplogroup is not displayed on the Big Y match page. If you happen to also match on STRs, their haplogroup is shown there as well. You can also search for their name using the block tree search function to view their haplogroup.

Necessity being the mother of invention, I created a combined match/block tree/haplotree.

And I really, REALLY hope Family Tree DNA implements something like this because, trust me, this was NOT fun! However, now that it’s done, it is extremely useful. With fewer matches, it should be a breeze.

Here are the steps to create the combined reference tree.

Combo Match/Block/Haplotree

I used Snagit to grab screenshots of the various portions of the haplotree and typed the surnames of the matches in the location of our common convergent haplogroup, taken from the spreadsheet. I also added the SNP generations in red for that haplogroup, at far left, to get some idea of when that common ancestor occurred.

McNIel Big Y combo tree

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This is, in essence, the end-goal of this exercise. There are a few steps to gather data.

Following the path of two matches (the tester and a specific match) you can find their common haplogroup. If your match is shown on the block tree in the same view with your branch, it’s easy to see your common convergent parent haplogroup. If you can’t see the common haplogroup, it’s takes a few extra steps by clicking up the block tree, as illustrated in an earlier section.

We need the ability to click on a match and have a tree display showing both paths to the common haplogroup.

McNiel Big Y convergent

I simulated this functionality in a spreadsheet with my McNiel cousin, a Riley match, and an Ocain match whose terminal SNP is the convergent SNP (M222) between Riley and McNiel. Of course, I’d also like to be able to click to see everyone on one chart on their appropriate branches.

Combining this information onto the haplotree, in the first image, below, M222, 4 men match my McNeill cousin – 2 who show M222 as their terminal SNP, and 2 downstream of M222 on a divergent branch that isn’t our direct branch. In other words, M222 is the convergence point for all 4 men plus my McNeill cousin.

McNiel Big Y M222 haplotree

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In the graphic below, you can see that M222 has a very large number of equivalent SNPs, which will likely become downstream haplogroups at some point in the future. However, today, these equivalent SNPs push M222 from 25 generations to 59. We’ll discuss how this meshes with known history in a minute.

McNiel Big Y M222 block tree

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Two men, Ocain and Ransom, who have both taken the Big Y, whose terminal SNP is M222, match my McNiel cousin. If their common ancestor was actually 59 generations in the past, it’s very, very unlikely that they would match at all given the 30 mutation threshold.

On my reconstructed Match/Block/Haplotree, I included the estimated SNP generations as well. We are starting with the most distant haplogroups and working our way forward in time with the graphics, below.

Make no mistake, there are thousands more men who descend from M222 that have tested, but all of those men except 4 have more than 30 mutations total, so they are not shown as Big Y matches, and they are not shown individually on the Block Tree because they neither match on the Big Y or STR tests. However, there is a way to view information for non-matching men who test positive for M222.

McNiel Big Y M222 countries

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Looking at the Block Tree for M222, many STR match men took a SNP test only to confirm M222, so they would be shown positive for the M222 SNP on STR results and, therefore, in the detailed view of M222 on the Block tree.

Haplogroup information about men who took the M222 test and whom the tester doesn’t match at all are shown here as well in the country and branch totals for R-M222. Their names aren’t displayed because they don’t match the tester on either type of Y DNA test.

Back to constructing my combined tree, I’ve left S658 in both images, above and below, as an overlap placeholder, as we move further down, or towards current, on the haplotree.

McNiel Big Y combo tree center

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Note that BY18350, above, is also an overlap connecting below.

You’ll recall that as a result of the Big Y test, BY18350 was split and now has three child branches plus one person whose terminal SNP is BY18350. All of the men shown below were on one branch until Big Y results revealed that BY18350 needed to be split, with multiple new haplogroups added to the tree.

McNiel Big Y combo tree current

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Using this combination of tools, it’s straightforward for me to see now that our McNiel line is closest to the Campbell tester from Scotland according to the Big Y test + STRs.

Equal according to the Big Y test, but slightly more distant, according to STR matching, is McCollum. The next closest would be sibling branches. Then in the parent group of the other three, BY18350, we find Glass from Scotland.

In BY18350 and subgroups, we find several Scotland locations and one Northern Ireland, which was likely from Scotland initially, given the surname and Ulster Plantation era.

The next upstream parent haplogroup is BY3344, which looks to be weighted towards ancestors from Scotland, shown on the country card, below.

McNiel Big Y BY3344

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This suggests that the origins of the McNiel line was, perhaps, in Scotland, but it doesn’t tell us whether or not George and presumably, Thomas, immigrated from Ireland or Scotland.

This combined tree, with SNPs, surnames from Big Y matches, along with Country information, allows me to see who is really more closely related and who is further away.

What I didn’t do, and probably should, is to add in all of the STR matches who have taken the Big Y test, shown on their convergent branch – but that’s just beyond the scope of time I’m willing to invest, at least for now, given that hundreds of STR matches have taken the Big Y test, and the work of building the combined tree is all manual today.

For those reading this article without access to the Y phylogenetic tree, there’s a public version of the Y and mitochondrial phylotrees available, here.

What About Those McNiels?

No other known McNiel descendants from either Thomas or George have taken the Big Y test, so I didn’t expect any to match, but I am interested in other men by similar surnames. Does ANY other McNiel have a Big Y match?

As it turns out, there are two, plus one STR match who took a Big Y test, but is not a Big Y match.

However, as you can see on the combined match/block/haplotree, above, the closest other Big Y-matching McNeil male is found at about 19 SNP generations, or roughly 1900 years ago. Even if you remove some of the variants in the lower generations that are based on an average number of individual variants, you’re still about 1200 years in the past. It’s extremely doubtful that any surname would survive in both lines from the year 800 or so.

That McNeil tester’s ancestor was born in 1747 in Tranent, Scotland.

The second Big Y-matching person is an O’Neil, a few branches further up in the tree.

The convergent SNP of the two branches, meaning O’Neil and McNeill are at approximately the 21 generation level. The O’Neil man’s Neill ancestor is found in 1843 in Cookestown, County Tyrone, Ireland.

McNiel Big Y convergent McNeil lines

I created a spreadsheet showing convergent lines:

  • The McNeill man with haplogroup A4697 (ancestor Tranent, Scotland) is clearly closest genetically.
  • O’Neill BY91591, who is brother clades with Neel and Neal, all Irish, is another Big Y match.
  • The McNeill man with haplogroup FT91182 is an STR match, but not a Big Y match.

The convergent haplogroup of all of these men is DF105 at about the 22 SNP generation marker.

STRs

Let’s turn back to STR tests, with results that produce matches closer in time.

Searching my STR download spreadsheet for similar surnames, I discovered several surname matches, mining the Earliest Known Ancestor information, profiles and trees produced data as follows:

Ancestor STR Match Level Location
George Charles Neil 12, 25, match on Big Y A4697 1747-1814 Tranent, Scotland
Hugh McNeil 25 (tested at 67) Born 1800 Country Antrim, Northern Ireland
Duncan McNeill 12 (tested at 111) Married 1789, Argyllshire, Scotland
William McNeill 12, 25 (tested at 37) Blackbraes, Stirlingshire, Scotland
William McNiel 25 (tested at 67) Born 1832 Scotland
Patrick McNiel 25 (tested at 111) Trien East, County Roscommon, Ireland
Daniel McNeill 25 (tested at 67) Born 1764 Londonderry, Northern Ireland
McNeil 12 (tested at 67) 1800 Ireland
McNeill (2 matches) 25 (tested Big Y-  SNP FT91182) 1810, Antrim, Northern Ireland
Neal 25 – (tested Big Y, SNP BY146184) Antrim, Northern Ireland
Neel (2 matches) 67 (tested at 111, and Big Y) 1750 Ireland, Northern Ireland

Our best clue that includes a Big Y and STR match is a descendant of George Charles Neil born in Tranent, Scotland, in 1747.

Perhaps our second-best clue comes in the form of a 111 marker match to a descendant of one Thomas McNeil who appears in records as early as 1753 and died in 1761 In Rombout Precinct, Dutchess County, NY where his son John was born. This line and another match at a lower level both reportedly track back to early New Hampshire in the 1600s.

The MacNeil DNA Project tells us the following:

Participant 106370 descends from Isaiah McNeil b. 14 May 1786 Schaghticoke, Rensselaer Co. NY and d. 28 Aug 1855 Poughkeepsie, Dutchess Co., NY, who married Alida VanSchoonhoven.

Isaiah’s parents were John McNeal, baptized 21 Jun 1761 Rombout, Dutchess Co., NY, d. 15 Feb 1820 Stillwater, Saratoga Co., NY and Helena Van De Bogart.

John’s parents were Thomas McNeal, b.c. 1725, d. 14 Aug 1761 NY and Rachel Haff.

Thomas’s parents were John McNeal Jr., b. around 1700, d. 1762 Wallkill, Orange Co., NY (now Ulster Co. formed 1683) and Martha Borland.

John’s parents were John McNeal Sr. and ? From. It appears that John Sr. and his family were this participant’s first generation of Americans.

Searching this line on Ancestry, I discovered additional information that, if accurate, may be relevant. This lineage, if correct, and it may not be, possibly reaching back to Edinburgh, Scotland. While the information gathered from Ancestry trees is certainly not compelling in and of itself, it provides a place to begin research.

Unfortunately, based on matches shown on the MacNeil DNA Project public page, STR marker mutations for kits 30279, B78471 and 417040 when compared to others don’t aid in clustering or indicating which men might be related to this group more closely than others using line-marker mutations.

Matches Map

Let’s take a look at what the STR Matches Map tells us.

McNiel Big Y matches map menu

This 67 marker Matches Map shows the locations of the earliest known ancestors of STR matches who have entered location information.

McNiel Big Y matches mapMcNiel Big Y matches map legend

My McNeill cousin’s closest matches are scattered with no clear cluster pattern.

Unfortunately, there is no corresponding map for Big Y matches.

SNP Map

The SNP map provided under the Y DNA results allows testers to view the locations where specific haplogroups are found.

McNiel Big Y SNP map

The SNP map marks an area where at least two or more people have claimed their most distant known ancestor to be. The cluster size is the maximum amount of miles between people that is allowed in order for a marker indicating a cluster at a location to appear. So for example, the sample size is at least 2 people who have tested, and listed their most distant known ancestor, the cluster is the radius those two people can be found in. So, if you have 10 red dots, that means in 1000 miles there are 10 clusters of at least two people for that particular SNP. Note that these locations do NOT include people who have tested positive for downstream locations, although it does include people who have taken individual SNP tests.

Working my way from the McNiel haplogroup backward in time on the SNP map, neither BY18332 nor BY18350 have enough people who’ve tested, or they didn’t provide a location.

Moving to the next haplogroup up the tree, two clusters are formed for BY3344, shown below.

McNIel Big Y BY3344 map

S668, below.

McNiel Big Y S668 map

It’s interesting that one cluster includes Glasgow.

S673, below.

McNiel Big Y S673 map

DF85, below:

McNiel Big Y DF85 map

DF105 below:

McNiel BIg Y DF105 map

M222, below:

McNiel Big Y M222 map

For R-M222, I’ve cropped the locations beyond Ireland and Scotland. Clearly, RM222 is the most prevalent in Ireland, followed by Scotland. Wherever M222 originated, it has saturated Ireland and spread widely in Scotland as well.

R-M222

R-M222, the SNP initially thought to indicate Niall of the 9 Hostages, occurred roughly 25-59 SNP generations in the past. If this age is even remotely accurate, averaging by 80 years per generation often utilized for Big Y results, produces an age of 2000 – 4720 years. I find it extremely difficult to believe any semblance of a surname survived that long. Even if you reduce the time in the past to the historical narrative, roughly the year 400, 1600 years, I still have a difficult time believing the McNiel surname is a result of being a descendant of Niall of the 9 Hostages directly, although oral history does have staying power, especially in a clan setting where clan membership confers an advantage.

Surname or not, clearly, our line along with the others whom we match on the Big Y do descend from a prolific common ancestor. It’s very unlikely that the mutation occurred in Niall’s generation, and much more likely that other men carried M222 and shared a common ancestor with Niall at some point in the distant past.

McNiel Conclusion – Is There One?

If I had two McNiel wishes, they would be:

  • Finding records someplace in Virginia that connect George and presumably brothers Thomas and John to their parents.
  • A McNiel male from wherever our McNiel line originated becoming inspired to Y DNA test. Finding a male from the homeland might point the way to records in which I could potentially find baptismal records for George about 1720 and Thomas about 1724, along with possibly John, if he existed.

I remain hopeful for a McNiel from Edinburgh, or perhaps Glasgow.

I feel reasonably confident that our line originated genetically in Scotland. That likely precludes Niall of the 9 Hostages as a direct ancestor, but perhaps not. Certainly, one of his descendants could have crossed the channel to Scotland. Or, perhaps, our common ancestor is further back in time. Based on the maps, it’s clear that M222 saturates Ireland and is found widely in Scotland as well.

A great deal depends on the actual age of M222 and where it originated. Certainly, Niall had ancestors too, and the Ui Neill dynasty reaches further back, genetically, than their recorded history in Ireland. Given the density of M222 and spread, it’s very likely that M222 did, in fact, originate in Ireland or, alternatively, very early in Scotland and proliferated in Ireland.

If the Ui Neill dynasty was represented in the persona of the High King, Niall of the 9 Hostages, 1600 years ago, his M222 ancestors were clearly inhabiting Ireland earlier.

We may not be descended from Niall personally, but we are assuredly related to him, sharing a common ancestor sometime back in the prehistory of Ireland and Scotland. That man would sire most of the Irish men today and clearly, many Scots as well.

Our ancestors, whoever they were, were indeed in Ireland millennia ago. R-M222, our ancestor, was the ancestor of the Ui Neill dynasty and of our own Reverend George McNiel.

Our ancestors may have been at Knowth and New Grange, and yes, perhaps even at Tara.

Tara Niall mound in sun

Someplace in the mists of history, one man made a different choice, perhaps paddling across the channel, never to return, resulting in M222 descendants being found in Scotland. His descendants include our McNeil ancestors, who still slumber someplace, awaiting discovery.

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DNA Inherited from Grandparents and Great-Grandparents

Philip Gammon, our statistician friend has been working with crossover simulations again in order to tell us what we might expect relative to how much DNA we actually inherit from grandparents and great-grandparents.

We know that on average, we’re going to inherit 25% of our DNA from each grandparent – but we also know in reality that’s not what happens. We get more or less than exactly 25% from each person in a grandparent pair. It’s the total of the DNA of both grandparents that adds up to 50% for the couple.

How does this work, and does it make a difference whether we inherit our grandparent’s DNA through males or females?

Philip has answers for us as a result of his simulations.

DNA Inheritance from Grandparents

Philip Gammon:

When we consider the DNA that we inherit from our ancestors the only quantity that we can be certain of is that we receive half of our autosomal DNA from each parent. This is delivered to us in the form of the 22 segments (i.e. chromosomes) provided by our mothers in the ova and the 22 segments/chromosomes provided by our fathers in the sperm cell. Beyond parent-child relationships we tend to talk about averages. For instance, we receive an average of one quarter of our DNA from each of our four grandparents and an average of one-eighth of our DNA from each of our eight great-grandparents etc.

These figures vary because our parents didn’t necessarily pass on to us equal portions of the DNA that they received from their parents. The level of variation is driven by the number (and location) of crossover events that occur when the ova and the sperm cells are created.

The statistics relevant to the recombination process were discussed in detail in a previous article (Crossovers: Frequency and Inheritance Statistics – Male Versus Female Matters). With the availability these days of abundant real data from direct-to-consumer genetic testing companies (such as the 23andMe data utilised by Campbell et. al. in their paper titled “Escape from crossover interference increases with maternal age”) we can use this information as a basis for simulations that accurately mimic the crossover process. From these simulations we can measure the amount of variation that is expected to be observed in the proportions of DNA inherited from our ancestors. This is precisely what I have done in simulations run on my GAT-C model.

Before looking at the simulation results let’s anticipate what we expect to see. The previous article on crossover statistics revealed that there are an average of about 42 crossovers in female meiosis and about 27 in male meiosis. So, on the set of 22 chromosomes received from our mothers there will have been an average of 42 crossover locations where there was a switch between DNA she inherited from one parent to the other. That means that the DNA we inherit from our maternal grandparents typically comes in about 64 segments, but it won’t necessarily be 32 segments from each maternal grandparent. Chromosomes that experienced an odd number of crossovers contain an even number of segments (half originating from the grandmother, the other half from the grandfather) but chromosomes with an even number of crossovers (or zero!) have an odd number of segments so on these chromosomes you must receive one more segment from one grandparent than the other. And of course not all segments are the same size either. A single crossover occurring close to one end of the chromosome results in a small segment from one grandparent and a large segment from the other. All up there are quite a few sources of variation that can affect the amount of DNA inherited from grandparents. The only certainty here is that the amount inherited from the two maternal grandparents must add to 50%. If you inherit more than the average of 25% from one maternal grandparent that must be offset by inheriting less than 25% from the other maternal grandparent.

Gammon grandparents maternal percent.png

The above chart shows the results of 100,000 simulation runs. Excluding the bottom and top 1% of results, 98% of people will receive between 18.7% and 31.3% of their DNA from a maternal grandparent. The more darkly shaded region in the centre shows the people who receive a fairly even split of between 24% and 26% from the maternal grandparents. Only 28.8% of people are in this region and the remainder receive a less even contribution.

On the set of 22 chromosomes received from fathers there will have been an average of around 27 crossovers so the DNA received from the paternal grandparents has only been split into around 49 segments. It’s the same amount of DNA as received from mothers but just in larger chunks of the grandparent’s DNA. This creates greater opportunity for the father to pass on unequal amounts of DNA from the two grandparents so it would be expected that results from paternal inheritance will show more variation than from maternal inheritance.

Gammon grandparents paternal percent.png

The above chart shows the results of 100,000 simulated paternal inheritance events. They are more spread out than the maternal events with the middle 98% of people receiving between 16.7% and 33.3% of their DNA from a paternal grandparent. Only 21.9% of people receive a fairly even split of between 24% and 26% from each paternal grandparent as shown by the more darkly shaded region in the centre.

Gammon grandparents percent cM.png

To help with the comparison between maternal and paternal inheritance from grandparents the two distributions have been overlayed on the same scale in the chart above. And what are the chances of receiving a fairly even split of grandparents DNA from both your mother and your father? Only 6.3% of people can be expected to inherit an amount of between 24% and 26% of their DNA from all four grandparents.

Now I’ll extend the simulations out to the next generation and examine the variation in proportions of DNA inherited from the eight great-grandparents. There are effectively four groups of great-grandparents:

  • Mother’s maternal grandparents
  • Mother’s paternal grandparents
  • Father’s maternal grandparents
  • Father’s paternal grandparents

The DNA from group 1 has passed to you via two maternal recombination events, from your mother’s mother to your mother, then from your mother to you. On average there would have been 42 crossovers in each of these recombination events. Group 4 comprised two paternal recombination events averaging only 27 crossovers in each. The average amount of DNA received along each path is the same but along the group 1 path it would comprise of more numerous smaller segments than the group 4 path. Groups 2 and 3 would be somewhere between, both consisting of one maternal and one paternal recombination event.

Gammon greatgrandparents percent cM.png

The above chart shows the variation in the amount of DNA received from members of the four groups of great-grandparents. 25,000 simulations were performed. The average amount from any great-grandparent is 12.5% but there can be considerably more variation in the amount received from the father’s paternal grandparents than from the mother’s maternal grandparents. Groups 2 and 3 are between these two extremes and are equivalent. It doesn’t matter whether a paternal recombination follows a maternal one or vice versa – the end result is that both paths consist of the same average number of crossovers.

The table below shows the range in the amount of DNA that people receive from their great-grandparents. The bottom and top 1% of outcomes have been excluded. Note that these are based on a total of 3,418 cM for the 22 autosomes which is the length observed in the Campbell et. al. study. The average of 12.5% of total DNA is 854.5 cM:

Group 1st percentile 99th percentile
Mother’s maternal grandparents 522 cM 1219 cM
Mother’s paternal grandparents 475 cM 1282 cM
Father’s maternal grandparents 475 cM 1281 cM
Father’s paternal grandparents 426 cM 1349 cM

As a matter of interest, in each of the 25,000 simulations the amount of DNA received from the eight great-grandparents were sorted into order from the highest cM to the lowest cM. The averages of each of these eight amounts were then calculated and the results are below:

Gammon greatgrandparents average cM.png

On average, a person receives 1,129 cM from the great-grandparent that they inherited the most of their DNA from and only 600 cM from the great-grandparent that they received the least of their DNA from. But none of us are the result of 25,000 trials – we are each the product of recombination events that occurred once only. The above chart shows the average or typical variation in the amount of DNA received from the eight great-grandparents. Half of people will have experienced more variation than shown above and half of people will have experienced less variation.

Could you have received the same amount of DNA from all eight grandparents? Of course, it is possible, but it turns out that it is extremely unlikely. The average is 12.5% (854.5 cM) so anything between 12% (820.4 cM) and 13% (888.7 cM) could be considered as being close to this figure. The results reveal that this did not occur in any of the 25,000 simulations. Not one person received amounts between 12% and 13% from all eight great-grandparents.

Widening the criteria, I observe that there were 13 instances in the 25,000 simulations where people received between 11.5% and 13.5% of their DNA from all eight great-grandparents. That is still an extremely rare occurrence. Expanding the range further to between 11% and 14% saw a total of 126 instances, but this still only represents about half a percent of all observations. I think that we just have to face the fact that unless we are an extremely rare individual then we will not have inherited close to equal amounts of DNA from our eight great-grandparents.

Now, back to Roberta.

Thanks Philip.

Now we see why we might not inherit the same amount of DNA from our grandparents and great-grandparents.

We Don’t Have Equal Numbers of Matches on Tree Branches

This also might explain, at least in part, why people don’t have the same number of DNA matches on each branch of their tree.

Of course, other reasons include:

  • Uneven family sizes
  • Fewer or more cousins testing on different branches
  • Recent immigration meaning there are few people available to test
  • Family from a region where DNA testing and/or genealogy is not popular
  • Endogamy which dramatically increases the number of people you will match

Real Life Example

In our real-life example, two grandchildren are fortunate to have three grandparents and one great-grandparent available for matching.

For comparison purposes, let’s take a look at how many matches each grandchild has in common with their grandparents and great-grandparent.

The line of descent is as follows:

Gammon line of descent.png

Both end of line testers are female children.

The transmission path from their great-grandmother is:

  • Female to their paternal grandmother
  • Female to their father
  • Male to female tester

The transmission path from their maternal grandfather is:

  • Male to their mother
  • Female to female tester

The transmission path from their maternal grandmother is:

  • Female to their mother
  • Female to female tester

This first chart shows the number of common matches.

Matches Grand 1 Grand 2 GGF GGM Grand 3 Grand 4
Female 1 absent 1061 absent 238 529 1306
Female 2 absent 1225 absent 431 700 1064

It’s interesting that the matches in just 3 generations to the great-grandmother vary by 55%. The second tester has almost twice as many matches in common with her great-great-grandmother as she does the first tester. There a difference in the earlier generation, meaning matches to Grand 2, but only about 23%. That difference increased significantly in one generation.

The second chart shows the total number of matching cM with the matching family member.

Total cM Grand 1 Grand 2 GGF GGM Grand 3 Grand 4
Female 1 absent 1688 absent 713 1601 1818
Female 2 absent 1750 absent 852 1901 1511

We can see that the amount of DNA inherited from a grandparent does correlate with the number of matches to that grandparents. The more DNA shared, of course the better the chances of sharing that DNA with another person. However, multiple factors may be involved with why some people have more or fewer matches.

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I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

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Hit a Genetic Genealogy Home Run Using Your Double-Sided Two-Faced Chromosomes While Avoiding Imposters

Do you want to hit a home run with your DNA test, but find yourself a mite bewildered?

Yep, those matches can be somewhat confusing – especially if you don’t understand what’s going on. Do you have a nagging feeling that you might be missing something?

I’m going to explain chromosome matching, and its big sister, triangulation, step by step to remove any confusion, to help you sort through your matches and avoid imposters.

This article is one of the most challenging I’ve ever written – in part because it’s a concept that I’m so familiar with but can be, and is, misinterpreted so easily. I see mistakes and confusion daily, which means that resulting conclusions stand a good chance of being wrong.

I’ve tried to simplify these concepts by giving you easy-to-use memory tools.

There are three key phrases to remember, as memory-joggers when you work through your matches using a chromosome browser: double-sided, two faces and imposter. While these are “cute,” they are also quite useful.

When you’re having a confusing moment, think back to these memory-jogging key words and walk yourself through your matches using these steps.

These three concepts are the foundation of understanding your matches, accurately, as they pertain to your genealogy. Please feel free to share, link or forward this article to your friends and especially your family members (including distant cousins) who work with genetic genealogy. 

Now, it’s time to enjoy your double-sided, two-faced chromosomes and avoid those imposters:)

Are you ready? Grab a nice cup of coffee or tea and learn how to hit home runs!

Double-Sided – Yes, Really

Your chromosomes really are double sided, and two-faced too – and that’s a good thing!

However, it’s initially confusing because when we view our matches in a chromosome browser, it looks like we only have one “bar” or chromosome and our matches from both our maternal and paternal sides are both shown on our one single bar.

How can this be? We all have two copies of chromosome 1, one from each parent.

Chromosome 1 match.png

This is my chromosome 1, with my match showing in blue when compared to my chromosome, in gray, as the background.

However, I don’t know if this blue person matches me on my mother’s or father’s chromosome 1, both of which I inherited. It could be either. Or neither – meaning the dreaded imposter – especially that small blue piece at left.

What you’re seeing above is in essence both “sides” of my chromosome number 1, blended together, in one bar. That’s what I mean by double-sided.

There’s no way to tell which side or match is maternal and which is paternal without additional information – and misunderstanding leads to misinterpreting results.

Let’s straighten this out and talk about what matches do and don’t mean – and why they can be perplexing. Oh, and how to discover those imposters!

Your Three Matches

Let’s say you have three matches.

At Family Tree DNA, the example chromosome browser I’m using, or at any vendor with a chromosome browser, you select your matches which are viewed against your chromosomes. Your chromosomes are always the background, meaning in this case, the grey background.

Chromosome 1-4.png

  • This is NOT three copies each of your chromosomes 1, 2, 3 and 4.
  • This is NOT displaying your maternal and paternal copies of each chromosome pictured.
  • We CANNOT tell anything from this image alone relative to maternal and paternal side matches.
  • This IS showing three individual people matching you on your chromosome 1 and the same three people matching you in the same order on every chromosome in the picture.

Let’s look at what this means and why we want to utilize a chromosome browser.

I selected three matches that I know are not all related through the same parent so I can demonstrate how confusing matches can be sorted out. Throughout this article, I’ve tried to explain each concept in at least two ways.

Please note that I’m using only chromsomes 1-4 as examples, not because they are any more, or less, important than the other chromosomes, but because showing all 22 would not add any benefit to the discussion. The X chromosome has a separate inheritance path and I wrote about that here.

Let’s start with a basic question.

Why Would I Want to Use a Chromosome Browser?

Genealogists view matches on chromosome browsers because:

  • We want to see where our matches match us on our chromosomes
  • We’d like to identify our common ancestor with our match
  • We want to assign a matching segment to a specific ancestor or ancestral line, which confirmed those ancestors as ours
  • When multiple people match us on the same location on the chromosome browser, that’s a hint telling us that we need to scrutinize those matches more closely to determine if those people match us on our maternal or paternal side which is the first step in assigning that segment to an ancestor

Once we accurately assign a segment to an ancestor, when anyone else matches us (and those other people) on that same segment, we know which ancestral line they match through – which is a great head start in terms of identifying our common ancestor with our new match.

That’s a genetic genealogy home run!

Home Runs 

There are four bases in a genetic genealogy home run.

  1. Determine whether you actually match someone on the same segment
  2. Which is the first step in determining that you match a group of people on the same segment
  3. And that you descend from a common ancestor
  4. The fourth step, or the home run, is to determine which ancestor you have in common, assigning that segment to that ancestor

If you can’t see segment information, you can’t use a chromosome browser and you can’t confirm the match on that segment, nor can you assign that segment to a particular ancestor, or ancestral couple.

The entire purpose of genealogy is to identify and confirm ancestors. Genetic genealogy confirms the paper trail and breaks down even more brick walls.

But before you can do that, you have to understand what matches mean and how to use them.

The first step is to understand that our chromosomes are double-sided and you can’ t see both of your chromosomes at once!

Double Sided – You Can’t See Both of Your Chromosomes at Once

The confusing part of the chromosome browser is that it can only “see” your two chromosomes blended as one. They are both there, but you just can’t see them separately.

Here’s the important concept:

You have 2 copies of chromosomes 1 through 22 – one copy that you received from your mother and one from your father, but you can’t “see” them separately.

When your DNA is sequenced, your DNA from your parents’ chromosomes emerges as if it has been through a blender. Your mother’s chromosome 1 and your father’s chromosome 1 are blended together. That means that without additional information, the vendor can’t tell which matches are from your father’s side and which are from your mother’s side – and neither can you.

All the vendor can tell is that someone matches you on the blended version of your parents. This isn’t a negative reflection on the vendors, it’s just how the science works.

Chromosome 1.png

Applying this to chromosome 1, above, means that each segment from each person, the blue person, the red person and the teal person might match you on either one of your chromosomes – the paternal chromosome or the maternal chromosome – but because the DNA of your mother and father are blended – there’s no way without additional information to sort your chromosome 1 into a maternal and paternal “side.”

Hence, you’re viewing “one” copy of your combined chromosomes above, but it’s actually “two-sided” with both maternal and paternal matches displayed in the chromosome browser.

Parent-Child Matches

Let’s explain this another way.

Chromosome parent.png

The example above shows one of my parents matching me. Don’t be deceived by the color blue which is selected randomly. It could be either parent. We don’t know.

You can see that I match my parent on the entire length of chromosome 1, but there is no way for me to tell if I’m looking at my mother’s match or my father’s match, because both of my parents (and my children) will match me on exactly the same locations (all of them) on my chromosome 1.

Chromosome parent child.png

In fact, here is a combination of my children and my parents matching me on my chromosome 1.

To sort out who is matching on paternal and maternal chromosomes, or the double sides, I need more information. Let’s look at how inheritance works.

Stay with me!

Inheritance Example

Let’s take a look at how inheritance works visually, using an example segment on chromosome 1.

Chromosome inheritance.png

In the example above:

  • The first column shows addresses 1-10 on chromosome 1. In this illustration, we are only looking at positions, chromosome locations or addresses 1-10, but real chromosomes have tens of thousands of addresses. Think of your chromosome as a street with the same house numbers on both sides. One side is Mom’s and one side is Dad’s, but you can’t tell which is which by looking at the house numbers because the house numbers are identical on both sides of the street.
  • The DNA pieces, or nucleotides (T, A, C or G,) that you received from your Mom are shown in the column labeled Mom #1, meaning we’re looking at your mother’s pink chromosome #1 at addresses 1-10. In our example she has all As that live on her side of the street at addresses 1-10.
  • The DNA pieces that you received from your Dad are shown in the blue column and are all Cs living on his side of the street in locations 1-10.

In other words, the values that live in the Mom and Dad locations on your chromosome streets are different. Two different faces.

However, all that the laboratory equipment can see is that there are two values at address 1, A and C, in no particular order. The lab can’t tell which nucleotide came from which parent or which side of the street they live on.

The DNA sequencer knows that it found two values at each address, meaning that there are two DNA strands, but the output is jumbled, as shown in the First and Second read columns. The machine knows that you have an A and C at the first address, and a C and A at the second address, but it can’t put the sequence of all As together and the sequence of all Cs together. What the sequencer sees is entirely unordered.

This happens because your maternal and paternal DNA is mixed together during the extraction process.

Chromosome actual

Click to enlarge image.

Looking at the portion of chromosome 1 where the blue and teal people both match you – your actual blended values are shown overlayed on that segment, above. We don’t know why the blue and the teal people are matching you. They could be matching because they have all As (maternal), all Cs (paternal) or some combination of As and Cs (a false positive match that is identical by chance.)

There are only two ways to reassemble your nucleotides (T, A, C, and G) in order and then to identify the sides as maternal and paternal – phasing and matching.

As you read this next section, it does NOT mean that you must have a parent for a chromosome browser to be useful – but it does mean you need to understand these concepts.

There are two types of phasing.

Parental Phasing

  • Parental Phasing is when your DNA is compared against that of one or both parents and sorted based on that comparison.

Chromosome inheritance actual.png

Parental phasing requires that at least one parent’s DNA is available, has been sequenced and is available for matching.

In our example, Dad’s first 10 locations (that you inherited) on chromosome 1 are shown, at left, with your two values shown as the first and second reads. One of your read values came from your father and the other one came from your mother. In this case, the Cs came from your father. (I’m using A and C as examples, but the values could just as easily be T or G or any combination.)

When parental phasing occurs, the DNA of one of your parents is compared to yours. In this case, your Dad gave you a C in locations 1-10.

Now, the vendor can look at your DNA and assign your DNA to one parent or the other. There can be some complicating factors, like if both your parents have the same nucleotides, but let’s keep our example simple.

In our example above, you can see that I’ve colored portions of the first and second strands blue to represent that the C value at that address can be assigned through parental phasing to your father.

Conversely, because your mother’s DNA is NOT available in our example, we can’t compare your DNA to hers, but all is not lost. Because we know which nucleotides came from your father, the remaining nucleotides had to come from your mother. Hence, the As remain after the Cs are assigned to your father and belong to your mother. These remaining nucleotides can logically be recombined into your mother’s DNA – because we’ve subtracted Dad’s DNA.

I’ve reassembled Mom, in pink, at right.

Statistical/Academic Phasing

  • A second type of phasing uses something referred to as statistical or academic phasing.

Statistical phasing is less successful because it uses statistical calculations based on reference populations. In other words, it uses a “most likely” scenario.

By studying reference populations, we know scientifically that, generally, for our example addresses 1-10, we either see all As or all Cs grouped together.

Based on this knowledge, the Cs can then logically be grouped together on one “side” and As grouped together on the other “side,” but we still have no way to know which side is maternal or paternal for you. We only know that normally, in a specific population, we see all As or all Cs. After assigning strings or groups of nucleotides together, the algorithm then attempts to see which groups are found together, thereby assigning genetic “sides.” Assigning the wrong groups to the wrong side sometimes happens using statistical phasing and is called strand swap.

Once the DNA is assigned to physical “sides” without a parent or matching, we still can’t identify which side is paternal and which is maternal for you.

Statistical or academic phasing isn’t always accurate, in part because of the differences found in various reference populations and resulting admixture. Sometimes segments don’t match well with any population. As more people test and more reference populations become available, statistical/academic phasing improves. 23andMe uses academic phasing for ethnicity, resulting in a strand swap error for me. Ancestry uses academic phasing before matching.

By comparison to statistical or academic phasing, parental phasing with either or both parents is highly accurate which is why we test our parents and grandparents whenever possible. Even if the vendor doesn’t use our parents’ results, we certainly can!

If someone matches you and your parent too, you know that match is from that parent’s side of your tree.

Matching

The second methodology to sort your DNA into maternal and paternal sides is matching, either with or without your parents.

Matching to multiple known relatives on specific segments assigns those segments of your DNA to the common ancestor of those individuals.

In other words, when I match my first cousin, and our genealogy indicates that we share grandparents – assuming we match on the appropriate amount of DNA for the expected relationship – that match goes a long way to confirming our common ancestor(s).

The closer the relationship, the more comfortable we can be with the confirmation. For example, if you match someone at a parental level, they must be either your biological mother, father or child.

While parent, sibling and close relationships are relatively obvious, more distant relationships are not and can occur though unknown or multiple ancestors. In those cases, we need multiple matches through different children of that ancestor to reasonably confirm ancestral descent.

Ok, but how do we do that? Let’s start with some basics that can be confusing.

What are we really seeing when we look at a chromosome browser?

The Grey/Opaque Background is Your Chromosome

It’s important to realize that you will see as many images of your chromosome(s) as people you have selected to match against.

This means that if you’ve selected 3 people to match against your chromosomes, then you’ll see three images of your chromosome 1, three images of your chromosome 2, three images of your chromosome 3, three images of your chromosome 4, and so forth.

Remember, chromosomes are double-sided, so you don’t know whether these are maternal or paternal matches (or imposters.)

In the illustration below, I’ve selected three people to match against my chromosomes in the chromosome browser. One person is shown as a blue match, one as a red match, and one as a teal match. Where these three people match me on each chromosome is shown by the colored segments on the three separate images.

Chromosome 1.png

My chromosome 1 is shown above. These images are simply three people matching to my chromosome 1, stacked on top of each other, like cordwood.

The first image is for the blue person. The second image is for the red person. The third image is for the teal person.

If I selected another person, they would be assigned a different color (by the system) and a fourth stacked image would occur.

These stacked images of your chromosomes are NOT inherently maternal or paternal.

In other words, the blue person could match me maternally and the red person paternally, or any combination of maternal and paternal. Colors are not relevant – in other words colors are system assigned randomly.

Notice that portions of the blue and teal matches overlap at some of the same locations/addresses, which is immediately visible when using a chromosome browser. These areas of common matching are of particular interest.

Let’s look closer at how chromosome browser matching works.

What about those colorful bars?

Chromosome Browser Matching

When you look at your chromosome browser matches, you may see colored bars on several chromosomes. In the display for each chromosome, the same color will always be shown in the same order. Most people, unless very close relatives, won’t match you on every chromosome.

Below, we’re looking at three individuals matching on my chromosomes 1, 2, 3 and 4.

Chromosome browser.png

The blue person will be shown in location A on every chromosome at the top. You can see that the blue person does not match me on chromosome 2 but does match me on chromosomes 1, 3 and 4.

The red person will always be shown in the second position, B, on each chromosome. The red person does not match me on chromosomes 2 or 4.

The aqua person will always be shown in position C on each chromosome. The aqua person matches me on at least a small segment of chromosomes 1-4.

When you close the browser and select different people to match, the colors will change and the stacking order perhaps, but each person selected will always be consistently displayed in the same position on all of your chromosomes each time you view.

The Same Address – Stacked Matches

In the example above, we can see that several locations show stacked segments in the same location on the browser.

Chromosome browser locations.png

This means that on chromosome 1, the blue and green person both match me on at least part of the same addresses – the areas that overlap fully. Remember, we don’t know if that means the maternal side or the paternal side of the street. Each match could match on the same or different sides.

Said another way, blue could be maternal and teal could be paternal (or vice versa,) or both could be maternal or paternal. One or the other or both could be imposters, although with large segments that’s very unlikely.

On chromosome 4, blue and teal both match me on two common locations, but the teal person extends beyond the length of the matching blue segments.

Chromosome 3 is different because all three people match me at the same address. Even though the red and teal matching segments are longer, the shared portion of the segment between all three people, the length of the blue segment, is significant.

The fact that the stacked matches are in the same places on the chromosomes, directly above/below each other, DOES NOT mean the matches also match each other.

The only way to know whether these matches are both on one side of my tree is whether or not they match each other. Do they look the same or different? One face or two? We can’t tell from this view alone.

We need to evaluate!

Two Faces – Matching Can be Deceptive!

What do these matches mean? Let’s ask and answer a few questions.

  • Does a stacked match mean that one of these people match on my mother’s side and one on my father’s side?

They might, but stacked matches don’t MEAN that.

If one match is maternal, and one is paternal, they still appear at the same location on your chromosome browser because Mom and Dad each have a side of the street, meaning a chromosome that you inherited.

Remember in our example that even though they have the same street address, Dad has blue Cs and Mom has pink As living at that location. In other words, their faces look different. So unless Mom and Dad have the same DNA on that entire segment of addresses, 1-10, Mom and Dad won’t match each other.

Therefore, my maternal and paternal matches won’t match each other either on that segment either, unless:

  1. They are related to me through both of my parents and on that specific location.
  2. My mother and father are related to each other and their DNA is the same on that segment.
  3. There is significant endogamy that causes my parents to share DNA segments from their more distant ancestors, even though they are not related in the past few generations.
  4. The segments are small (segments less than 7cM are false matches roughly 50% of the time) and therefore the match is simply identical by chance. I wrote about that here. The chart showing valid cM match percentages is shown here, but to summarize, 7-8 cMs are valid roughly 46% of the time, 8-9 cM roughly 66%, 9-10 cM roughly 91%, 10-11 cM roughly 95, but 100 is not reached until about 20 cM and I have seen a few exceptions above that, especially when imputation is involved.

Chromosome inheritance match.png

In this inheritance example, we see that pink Match #1 is from Mom’s side and matches the DNA I inherited from pink Mom. Blue Match #2 is from Dad’s side and matches the DNA I inherited from blue Dad. But as you can see, Match #1 and Match #2 do not match each other.

Therefore, the address is only half the story (double-sided.)

What lives at the address is the other half. Mom and Dad have two separate faces!

Chromosome actual overlay

Click to enlarge image

Looking at our example of what our DNA in parental order really looks like on chromosome 1, we see that the blue person actually matches on my maternal side with all As, and the teal person on the paternal side with all Cs.

  • Does a stacked match on the chromosome browser mean that two people match each other?

Sometimes it happens, but not necessarily, as shown in our example above. The blue and teal person would not match each other. Remember, addresses (the street is double-sided) but the nucleotides that live at that address tell the real story. Think two different looking faces, Mom’s and Dad’s, peering out those windows.

If stacked matches match each other too – then they match me on the same parental side. If they don’t match each other, don’t be deceived just because they live at the same address. Remember – Mom’s and Dad’s two faces look different.

For example, if both the blue and teal person match me maternally, with all As, they would also match each other. The addresses match and the values that live at the address match too. They look exactly the same – so they both match me on either my maternal or paternal side – but it’s up to me to figure out which is which using genealogy.

Chromosome actual maternal.png

Click to enlarge image

When my matches do match each other on this segment, plus match me of course, it’s called triangulation.

Triangulation – Think of 3

If my two matches match each other on this segment, in addition to me, it’s called triangulation which is genealogically significant, assuming:

  1. That the triangulated people are not closely related. Triangulation with two siblings, for example, isn’t terribly significant because the common ancestor is only their parents. Same situation with a child and a parent.
  2. The triangulated segments are not small. Triangulation, like matching, on small segments can happen by chance.
  3. Enough people triangulate on the same segment that descends from a common ancestor to confirm the validity of the common ancestor’s identity, also confirming that the match is identical by descent, not identical by chance.

Chromosome inheritance triangulation.png

The key to determining whether my two matches both match me on my maternal side (above) or paternal side is whether they also match each other.

If so, assuming all three of the conditions above are true, we triangulate.

Next, let’s look at a three-person match on the same segment and how to determine if they triangulate.

Three Way Matching and Identifying Imposters

Chromosome 3 in our example is slightly different, because all three people match me on at least a portion of that segment, meaning at the same address. The red and teal segments line up directly under the blue segment – so the portion that I can potentially match identically to all 3 people is the length of the blue segment. It’s easy to get excited, but don’t get excited quite yet.

Chromosome 3 way match.png

Given that three people match me on the same street address/location, one of the following three situations must be true:

  • Situation 1- All three people match each other in addition to me, on that same segment, which means that all three of them match me on either the maternal or paternal side. This confirms that we are related on the same side, but not how or which side.

Chromosome paternal.png

In order to determine which side, maternal or paternal, I need to look at their and my genealogy. The blue arrows in these examples mean that I’ve determined these matches to all be on my father’s side utilizing a combination of genealogy plus DNA matching. If your parent is alive, this part is easy. If not, you’ll need to utilize common matching and/or triangulation with known relatives.

  • Situation 2 – Of these three people, Cheryl, the blue bar on top, matches me but does not match the other two. Charlene and David, the red and teal, match each other, plus me, but not Cheryl.

Chromosome maternal paternal.png

This means that at least either my maternal or paternal side is represented, given that Charlene and David also match each other. Until I can look at the identity of who matches, or their genealogy, I can’t tell which person or people descend from which side.

In this case, I’ve determined that Cheryl, my first cousin, with the pink arrow matches me on Mom’s side and Charlene and David, with the blue arrows, match me on Dad’s side. So both my maternal and paternal sides are represented – my maternal side with the pink arrow as well as my father’s side with the blue arrows.

If Cheryl was a more distant match, I would need additional triangulated matches to family members to confirm her match as legitimate and not a false positive or identical by chance.

  • Situation 3 – Of the three people, all three match me at the same addresses, but none of the three people match each other. How is this even possible?

Chromosome identical by chance.png

This situation seems very counter-intuitive since I have only 2 chromosomes, one from Mom and one from Dad – 2 sidesof the street. It is confusing until you realize that one match (Cheryl and me, pink arrow) would be maternal, one would be paternal (Charlene and me, blue arrow) and the third (David and me, red arrows) would have DNA that bounces back and forth between my maternal and paternal sides, meaning the match with David is identical by chance (IBC.)

This means the third person, David, would match me, but not the people that are actually maternal and paternal matches. Let’s take a look at how this works

Chromosome maternal paternal IBC.png

The addresses are the same, but the values that live at the addresses are not in this third scenario.

Maternal pink Match #1 is Cheryl, paternal blue Match #2 is Charlene.

In this example, Match #3, David, matches me because he has pink and blue at the same addresses that Mom and Dad have pink and blue, but he doesn’t have all pink (Mom) nor all blue (Dad), so he does NOT match either Cheryl or Charlene. This means that he is not a valid genealogical match – but is instead what is known as a false positive – identical by chance, not by descent. In essence, a wily genetic imposter waiting to fool unwary genealogists!

In his case, David is literally “two-faced” with parts of both values that live in the maternal house and the paternal house at those addresses. He is a “two-faced imposter” because he has elements of both but isn’t either maternal or paternal.

This is the perfect example of why matching and triangulating to known and confirmed family members is critical.

All three people, Cheryl, Charlene and David match me (double sided chromosomes), but none of them match each other (two legitimate faces – one from each parent’s side plus one imposter that doesn’t match either the legitimate maternal or paternal relatives on that segment.)

Remember Three Things

  1. Double-Sided – Mom and Dad both have the same addresses on both sides of each chromosome street.
  2. Two Legitimate Faces – The DNA values, nucleotides, will have a unique pattern for both your Mom and Dad (unless they are endogamous or related) and therefore, there are two legitimate matching patterns on each chromsome – one for Mom and one for Dad. Two legitimate and different faces peering out of the houses on Mom’s side and Dad’s side of the street.
  3. Two-Faced Imposters – those identical by chance matches which zig-zag back and forth between Mom and Dad’s DNA at any given address (segment), don’t match confirmed maternal and paternal relatives on the same segment, and are confusing imposters.

Are you ready to hit your home run?

What’s Next?

Now that we understand how matching and triangulation works and why, let’s put this to work at the vendors. Join me for my article in a few days, Triangulation in Action at Family Tree DNA, MyHeritage, 23andMe and GedMatch.

We will step through how triangulation works at each vendor. You’ll have matches at each vendor that you don’ t have elsewhere. If you haven’t transferred your DNA file yet, you still have time with the step by step instructions below:

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Crossovers: Frequency and Inheritance Statistics – Male Versus Female Matters

Recently, a reader asked if I had any crossover statistics.

They were asking about the number of crossovers, meaning divisions on each chromosome, of the parent’s DNA when a child is created. In other words, how many segments of your maternal and paternal grandparent’s DNA do you inherit from your mother and father – and are those numbers somehow different?

Why would someone ask that question, and how is it relevant for genealogists?

What is a Crossover and Why is it Important?

We know that every child receives half of their autosomal DNA from their father, and half from their mother. Conversely that means that each parent can only give their child half of their own DNA that they received from their parents. Therefore, each parent has to combine some of the DNA from their father’s chromosome and their mother’s chromosome into a new chromosome that they contribute to their child.

Crossovers are breakpoints that are created when the DNA of the person’s parents is divided into pieces before being recombined into a new chromosome and passed on to the person’s child.

I’m going to use the following real-life scenario to illustrate.

Crossover pedigree.png

The colors of the people above are reflected on the chromosome below where the DNA of the blue daughter, and her red and green parents are compared to the DNA of the tester. The tester is shown as the gray background chromosomes in the chromosome browser. The backgroud person is whose results we are looking at.

My granddaughter has tested her DNA, as have her parents and 3 of her 4 grandparents along with 2 great-grandparents, shown as red and green in the diagram above.

Here’s an example utilizing the FamilyTreeDNA chromosome browser.

Crossover example chr 1.png

On my granddaughter’s chromosome 1, on the chromosome brower above, we see two perfect examples of crossovers.

There’s no need to compare her DNA against that of her parent, the son in the chart above, because we already know she matches the full length of every chromosome with both of her parents.

However, when comparing my granddaughter’s DNA against the grandmother (blue) and her grandmother’s parents, the great-grandmother shown in red and great-grandfather shown in green, we can see that the granddaughter received her blue segments from the grandmother.

The grandmother had to receive that entire blue segment from either her mother, in red, or her father, in green. So, every blue segment must have an exactly matching red segment, green segment or combination of both.

The first red box at left shows that the blue segment was inherited partially from the grandmother’s red mother and green father. We know that because the tester matches the red great-grandmother on part of that blue segment and the green great-grandfather on a different part of the entire blue segment that the tester inherited from her blue grandmother.

The middle colored region, not boxed, shows the entire blue segment was inherited from the red great-grandmother and the blue grandmother passed that intact through her son to her granddaughter.

The third larger red boxed area encompassing the entire tested region to the right of the centromere was inherited by the granddaughter from her grandmother (blue segment) but it was originally from the blue grandmother’s red mother and green father.

The Crossover

The areas on this chromosome where the blue is divided between the red and green, meaning where the red and green butt up against each other is called a crossover. It’s literally where the DNA of the blue daughter crosses over between DNA contributed by her red mother and green father.

Crossover segments.png

In other words, the crossover where the DNA divided between the blue grandmother’s parents when the grandmother’s son was created is shown by the dark arrows above. The son gave his daughter that exact same segment from his mother and it’s only by comparing the tester’s DNA against her great-grandparents that we can see the crossover.

Crossover 4 generations.png

What we’re really seeing is that the segments inherited by the grandmother from her parents two different chromosomes were combined into one segment that the grandmother gave to her son. The son inherited the green piece and the red piece on his maternal chromosome, which he gave intact to his daughter, which is why the daughter matches her grandmother on that entire blue segment and matches her great-grandparents on the red and green pieces of their individual DNA.

Inferred Matching Segments

Crossover untested grandfather.png

The entirely uncolored regions are where the tester does not match her blue grandmother and where she would match her grandfather, who has not tested, instead of her blue grandmother.

The testers father only received his DNA from his mother and father, and if his daughter does not match his mother, then she must match his untested father on that segment.

Looking at the Big Inheritance Picture

The tester’s full autosomal match between the blue grandmother, red great-grandmother and green great-grandfather is shown below.

Crossover autosomes.png

In light of the discussion that follows, it’s worth noting that chromosomes 4 and 20 (orange arrows) were passed intact from the blue grandmother to the tester through two meiosis (inheritance) events. We know this because the tester matches the green great-grandfather’s DNA entirely on these two chromosomes that he passed to his blue daughter, her son and then the tester.

Let’s track this for chromosomes 4 and 20:

  • Meiosis 1 –The tester matches her blue grandmother, so we know that there was no crossover on that segment between the father and the tester.
  • Meiosis 2 – The tester matches her green great-grandfather along the entire chromosome, proving that it was passed intact from the grandmother to the tester’s father, her son.
  • What we don’t know is whether there were any crossovers between the green great-grandfather when he passed his parent or parents DNA to the blue grandmother, his daughter. In order to determine that, we would need at least one of the green great-grandfather’s parents, which we don’t have. We don’t know if the green great-grandfather passed on his maternal or paternal copy of his chromosome, or parts of each to the blue great-grandmother, his daughter.

Meiosis Events and the Tree

So let’s look at these meiosis or inheritance events in a different way, beginning at the bottom with the pink tester and counting backwards, or up the tree.

Crossover meiosis events.png

By inference, we know that chromosomes 11, 16 and 22 (purple arrows) were also passed intact, but not from the blue grandmother. The tester’s father passed his father’s chromosome intact to his daughter. That’s the untested grandfather again. We know this because the tester does not match her blue grandmother at all on either of these three chromosomes, so the tester must match her untested grandfather instead, because those are the only two sources of DNA for the tester’s father.

A Blip, or Not?

If you’ve noticed that chromosome 14 looks unusual, in that the tester matches her grandmother’s blue segment, but not either of her great-grandparents, which is impossible, give yourself extra points for your good eye.

In this case, the green great-grandfather’s kit was a transfer kit in which that portion of chromosome 14 was not included or did not read accurately. Given that the red great-grandmother’s kit DID read in that region and does not match the tester, we know that chromosome 14 would actually have a matching green segment exactly the size of the blue segment.

However, in another situation where we didn’t know of an issue with the transfer kit, it is also possible that the granddaughter matched a small segment of the blue grandmother’s DNA where they were identical by chance. In that case, chromosome 14 would actually have been passed to the tester intact from her father’s father, who is untested.

Every Segment has a Story

Looking at this matching pattern and our ability to determine the source of the DNA back several generations, originating from great-grandparents, I hope you’re beginning to get a sense of why understanding crossovers better is important to genealogists.

Every single segment has a story and that story is comprised of crossovers where the DNA of our ancestors is combined in their offspring. Today, we see the evidence of these historical genetic meiosis or division/recombination events in the start and end points of matches to our genetic cousins. Every start and end point represents a crossover sometime in the past.

What else can we tell about these events and how often they occur?

Of the 22 autosomes, not counting the X chromosome which has a unique inheritance pattern, 17 chromosomes experienced at least one crossover.

What does this mean to me as a genealogist and how can I interpret this type of information?

Philip Gammon

You may remember our statistician friend Philip Gammon. Philip and I have collaborated before authoring the following articles where Philip did the heavy lifting.

I discussed crossovers in the article Concepts – DNA Recombination and Crossovers, also in collaboration with Philip, and showed several examples in a Four Generation Inheritance Study.

If you haven’t read those articles, now might be a good time to do so, as they set the stage for understanding the rest of this article.

The frequency of chromosome segment divisions and their resulting crossovers are key to understanding how recombination occurs, which is key to understanding how far back in time a common ancestor between you and a match can expect to be found.

In other words, everything we think we know about relationships, especially more distant relationships, is predicated on the rate that crossovers occur.

The Concepts article references the Chowdhury paper and revealed that females average about 42 crossovers per child and males average about 27 but these quantities refer to the total number of crossovers on all 22 autosomes and reveal nothing about the distribution of the number of crossovers at the individual chromosome level.

Philip Gammon has been taking a closer look at this particular issue and has done some very interesting crossover simulations by chromosome, which are different sizes, as he reports beginning here.

Crossover Statistics by Philip Gammon

For chromosomes there is surprisingly little information available regarding the variation in the number of crossovers experienced during meiosis, the process of cell division that results in the production of ova and sperm cells. In the scientific literature I have been able to find only one reference that provides a table showing a frequency distribution for the number of crossovers by chromosome.

The paper Broad-Scale Recombination Patterns Underlying Proper Disjunction in Humans by Fledel-Alon et al in 2009 contains this information tucked away at the back of the “Supplementary methods, figures, and tables” section. It was likely not produced with genetic genealogists in mind but could be of great interest to some. The columns X0 to X8 refer to the number of crossovers on each chromosome that were measured in parental transmissions. Separate tables are shown for male and female transmissions because the rates between the two sexes differ significantly. Note that it’s the gender of the parent that matters, not the child. The sample size is quite small, containing only 288 occurrences for each gender.

A few years ago I stumbled across a paper titled Escape from crossover interference increases with maternal age by Campbell et al 2015. This study investigated the properties of crossover placement utilising family groups contained within the database of the direct-to-consumer genetic testing company 23andMe. In total more than 645,000 well-supported crossover events were able to be identified. Although this study didn’t directly report the observed frequency distribution of crossovers per chromosome, it did produce a table of parameters that accurately described the distribution of inter-crossover distances for each chromosome.

By introducing these parameters into a model that I had developed to implement the equations described by Housworth and Stahl in their 2003 paper Crossover Interference in Humans I was able to derive tables depicting the frequency of crossovers. The following results were produced for each chromosome by running 100,000 simulations in my crossover model:

Crossover transmissions from female to child.png

Transmissions from female parent to child, above.

Crossover transmissions male to child.png

Transmissions from male parent to child.

To be sure that we understand what these tables are revealing let’s look at the first row of the female table. The most frequent outcome for chromosome #1 is that there will be three crossovers and this occurs 27% of the time. There were instances when up to 10 crossovers were observed in a single meiosis but these were extremely rare. Cells that are blank recorded no observations in the 100,000 simulations. On average there are 3.36 crossovers observed on chromosome #1 in female to child transmissions i.e. the female chromosome #1 is 3.36 Morgans (336 centimorgans) in genetic length.

Blaine Bettinger has since examined crossover statistics using crowdsourced data in The Recombination Project: Analyzing Recombination Frequencies Using Crowdsourced Data, but only for females. His sample size was 250 maternal transmissions and Table 2 in the report presents the results in the same format as the tables above. There is a remarkable degree of conformity between Blaine’s measurements and the output from my simulation model and also to the earlier Fledel-Alon et al study.

The diagrams below are a typical representation of the chromosomes inherited by a child.

Crossovers inherited from mother.jpg

The red and orange (above) are the set of chromosomes inherited from the mother and the aqua and green (below) from the father. The locations where the colours change identify the crossover points.

It’s worth noting that all chromosomes have a chance of being passed from parent to child without recombination. These probabilities are found in the column for zero crossovers.

In the picture above the mother has passed on two red chromosomes (#14 and #20) without recombination from one of the maternal grandparents. No yellow chromosomes were passed intact.

Similarly, below, the father has passed on a total of five chromosomes that have no crossover points. Blue chromosomes #15, #18 and #21 were passed on intact from one paternal grandparent and green chromosomes #4 and #20 from the other.

Crossovers inherited from father.jpg

It’s quite a rare event for one of the larger chromosomes to be passed on without recombination (only a 1.4% probability for chromosome #1 in female transmissions) but occurs far more frequently in the smaller chromosomes. In fact, the male chromosome #21 is passed on intact more often (50.6% of the time) than containing DNA from both of the father’s parents.

However, there is nothing especially significant about chromosome #21.

The same could be said for any region of similar genetic length on any of the autosomes i.e. the first 52 cM of chromosome #1 or the middle 52 cM of chromosome #10 etc. From my simulations I have observed that on average 2.8 autosomes are passed down from a mother to child without a crossover and an average of 5.1 autosomes from a father to child.

In total (from both parents), 94% of offspring will inherit between 4 and 12 chromosomes containing DNA exclusively from a single grandparent. In the 100,000 simulations the child always inherited at least one chromosome without recombination.

Back to Roberta

If you have 3 generations who have tested, you can view the crossovers in the grandchild as compared to either one or two grandparents.

If the child doesn’t match one grandparent, even if their other grandparent through that parent hasn’t tested, you can certainly infer that any DNA where the grandchild doesn’t match the available grandparent comes from the non-tested “other” grandparent on that side.

Let’s Look at Real-Life Examples

Using the example of my 2 granddaughters, both of their parents and 3 of their 4 grandparents have tested, so I was able to measure the crossovers that my granddaughters experienced from all 4 of their grandparents.

Maternal Crossovers Granddaughter 1 Granddaughter 2 Average
Chromosome 1 6 2 3.36
Chromosome 2 4 2 3.17
Chromosome 3 3 2 2.71
Chromosome 4 2 2 2.59
Chromosome 5 2 1 2.49
Chromosome 6 4 2 2.36
Chromosome 7 3 1 2.23
Chromosome 8 2 2 2.11
Chromosome 9 3 1 1.95
Chromosome 10 4 2 2.08
Chromosome 11 3 0 1.93
Chromosome 12 3 3 2.00
Chromosome 13 1 1 1.52
Chromosome 14 3 1 1.38
Chromosome 15 4 1 1.44
Chromosome 16 2 2 1.58
Chromosome 17 2 2 1.53
Chromosome 18 2 0 1.40
Chromosome 19 2 1 1.18
Chromosome 20 0 1 1.19
Chromosome 21 0 1 0.74
Chromosome 22 1 0 0.78
Total 56 30 41.71

Looking at these results, it’s easy to see just how different inheritance between two full siblings can be. Granddaughter 1 has 56 crossovers through her mother, significantly more than the average of 41.71. Granddaughter 2 has 30, significantly less than average.

The average of the 2 girls is 43, very close to the total average of 41.71.

Note that one child received 2 chromosomes intact from her mother, and the other received 3.

Paternal Crossovers Granddaughter 1 Granddaughter 2 Average
Chromosome 1 2 2 1.98
Chromosome 2 3 2 1.85
Chromosome 3 2 2 1.64
Chromosome 4 0 1 1.46
Chromosome 5 1 2 1.46
Chromosome 6 2 1 1.41
Chromosome 7 1 2 1.36
Chromosome 8 1 1 1.23
Chromosome 9 1 3 1.26
Chromosome 10 3 2 1.30
Chromosome 11 0 1 1.20
Chromosome 12 1 1 1.32
Chromosome 13 2 1 1.02
Chromosome 14 1 0 0.97
Chromosome 15 1 2 1.01
Chromosome 16 0 1 1.02
Chromosome 17 0 0 1.06
Chromosome 18 1 1 0.98
Chromosome 19 1 1 1.00
Chromosome 20 0 0 0.99
Chromosome 21 0 0 0.52
Chromosome 22 0 0 0.63
Total 23 26 26.65

Granddaughter 2 had slightly more paternal crossovers than did granddaughter 1.

One child received 7 chromosomes intact from her father, and the other received 5.

Chromosome Granddaughter 1 Maternal Granddaughter 1 Paternal
Chromosome 1 6 2
Chromosome 2 4 3
Chromosome 3 3 2
Chromosome 4 2 0
Chromosome 5 2 1
Chromosome 6 4 2
Chromosome 7 3 1
Chromosome 8 2 1
Chromosome 9 3 1
Chromosome 10 4 3
Chromosome 11 3 0
Chromosome 12 3 1
Chromosome 13 1 2
Chromosome 14 3 1
Chromosome 15 4 1
Chromosome 16 2 0
Chromosome 17 2 0
Chromosome 18 2 1
Chromosome 19 2 1
Chromosome 20 0 0
Chromosome 21 0 0
Chromosome 22 1 0
Total 56 23

Comparing each child’s maternal and paternal crossovers side by side, we can see that Granddaughter 1 has more than double the number of maternal as compared to paternal crossovers, while Granddaughter 2 only had slightly more.

Chromosome Granddaughter 2 Maternal Granddaughter 2 Paternal
Chromosome 1 2 2
Chromosome 2 2 2
Chromosome 3 2 2
Chromosome 4 2 1
Chromosome 5 1 2
Chromosome 6 2 1
Chromosome 7 1 2
Chromosome 8 2 1
Chromosome 9 1 3
Chromosome 10 2 2
Chromosome 11 0 1
Chromosome 12 3 1
Chromosome 13 1 1
Chromosome 14 1 0
Chromosome 15 1 2
Chromosome 16 2 1
Chromosome 17 2 0
Chromosome 18 0 1
Chromosome 19 1 1
Chromosome 20 1 0
Chromosome 21 1 0
Chromosome 22 0 0
Total 30 26

Granddaughter 2 has closer to the same number of maternal and paternal of crossovers, but about 8% more maternal.

Comparing Maternal and Paternal Crossover Rates

Given that males clearly have a much, much lower crossover rate, according to the Philip’s chart as well as the evidence in just these two individual cases, over time, we would expect to see the DNA segments significantly LESS broken up in male to male transmissions, especially an entire line of male to male transmissions, as compared to female to female linear transmissions. This means we can expect to see larger intact shared segments in a male to male transmission line as compared to a female to female transmission line.

  G1 Mat G2 Mat Mat Avg G1 Pat G2 Pat Pat Avg
Gen 1 56 30 41.71 23 26 26.65
Gen 2 112 60 83.42 46 52 53.30
Gen 3 168 90 125.13 69 78 79.95
Gen 4 224 120 166.84 92 104 106.60

Using the Transmission rates for Granddaughter 1, Granddaughter 2, and the average calculated by Philip, it’s easy to see the cumulative expected average number of crossovers vary dramatically in every generation.

By the 4th generation, the maternal crossovers seen in someone entirely maternally descended at the rate of Grandchild 1 would equal 224 crossovers meaning that the descendant’s DNA would be divided that many times, while the same number of paternal linear divisions at 4 generations would only equal 92.

Yet today, we would never look at 2 people’s DNA, one with 224 crossovers compared to one with 92 crossovers and even consider the possibility that they are both only three generations descended from an ancestor, counting the parents as generation 1.

What Does This Mean?

The number of males and females in a specific line clearly has a direct influence on the number of crossovers experienced, and what we can expect to see as a result in terms of average segment size of inherited segments in a specific number of generations.

Using Granddaughter 1’s maternal crossover rate as an example, in 4 generations, chromosome 1 would have incurred a total of 24 crossovers, so the DNA would be divided into in 25 pieces. At the paternal rate, only 8 crossovers so the DNA would be in 9 pieces.

Chromosome 1 is a total of 267 centimorgans in length, so dividing 267 cM by 25 would mean the average segment would only be 10.68 cM for the maternal transmission, while the average segment divided by 9 would be 29.67 cM in length for the paternal transmission.

Given that the longest matching segment is a portion of the estimated relationship calculation, the difference between a 10.68 cM maternal linear segment match and a 29.67 paternal linear cM segment match is significant.

While I used the highest and lowest maternal and paternal rates of the granddaughters, the average would be 19 and 29, respectively – still a significant difference.

Maternal and Paternal Crossover Average Segment Size

Each person has an autosomal total of 3374 cM on chromosomes 1-22, excluding the X chromosome, that is being compared to other testers. Applying these calculations to all 22 autosomes using the maternal and paternal averages for 4 generations, dividing into the 3374 total we find the following average segment centiMorgan matches:

Crossovers average segment size.png

Keep in mind, of course, that the chart above represents 3 generations in a row of either maternal or paternal crossovers, but even one generation is significant.

The average size segment of a grandparent’s DNA that a child receives from their mother is 80.89 cM where the average segment of a grandparent’s DNA inherited from their father is 1.57 times larger at 126.6 cM.

Keep the maternal versus paternal inheritance path in mind as you evaluate matches to cousins with identified common ancestors, especially if the path is entirely or mostly maternal or paternal.

For unknown matches, just keep in mind that the average that vendors calculate and use to predict relationships, because they can’t and don’t have “inside knowledge” about the inheritance path, may or may not be either accurate or average. They do the best they can do with the information they have at hand.

Back to Philip again who provides us with additional information.

Maternal Versus Paternal Descent

Along a predominantly maternal path the DNA is likely to be inherited in more numerous smaller segments while along a predominantly paternal path it will likely be in fewer but larger segments. So matches who descend paternally from a common ancestor and carry the surname are not likely to carry more DNA from that common male ancestor than someone who descends from a mixed or directly maternal line. In fact, someone descending from an ancestor down an all-male path is more likely to inherit no DNA at all from that ancestor than someone descending down an all-female path. This is because the fewer segments there are the higher the risk is that a person won’t pass on any of them. Of course, there’s also a greater chance that all of the segments could be passed on. Fewer segments leads to more variation in the amount of DNA inherited but not a higher average amount of DNA inherited.

Gammon 3X great-grandparents.png

The chart above shows the spread in the amount of DNA inherited from a 3xgreat-grandparent, down all-maternal, all-paternal and down all possible paths. The average in each case is 3.125% i.e. 1 part in 32 but as expected the all-paternal path shows much more variation. Compared to the all-maternal path, on the all-paternal you are more likely to inherit either less than 2.0% or more than 5.0%. In 50,000 simulations there were 14 instances where a 3xgreat-grandchild did not inherit any DNA down the all-paternal path. There were no cases of zero DNA inherited down the all-maternal path.

One way to think about this is to consider a single chromosome. If at least one crossovers occurs in the meiosis some DNA from each grandparent will be passed down to the grandchild but when it is passed on without recombination, as occurs more frequently in paternal than maternal meiosis, all of the DNA from one grandparent is passed on but none at all from the other. When this happens, there is no bias toward either the grandfather’s or the grandmother’s chromosome being passed on. It’s just as likely that the segment coming down the all-paternal path will be lost entirely as it is that it will be passed on in full.

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

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DNAPainter: Painting Leeds Method Matches

Last week, I wrote about how I utilized the Leeds Method in the article, The Leeds Method. What I didn’t say is that I was sizing up the Leeds Method for how I could use the technique to paint additional segments of my chromosomes.

The Leeds Method divides your matches into four groups, one attributable to each grandparent. That means those matches can be painted to your four sets of great-grandparents, assuming you can identify the maternal and paternal groups. Hint – Y and mitochondrial DNA matching or haplogroups may help if you have no better hints.

For genealogists who know who their grandparents are, testing close relatives and cousins is a must in order to be able to associate matches with your four grandparents’ lines.

Please note that the Leeds method generates hints for genealogists by grouping people according to common matches. We must further evaluate those matches by doing traditional genealogy and by looking for segments that triangulate. The Leeds method in conjunction with the actual match results at vendors, combined with DNAPainter helps us do just that.

Utilizing DNAPainter

Since I’ve been able to sort matches into maternal and paternal “sides” using the Leeds Method, which in essence parentally phases the matches, I can use DNAPainter to paint them. Here are my four articles I wrote about how to utilize DNAPainter.

DNAPainter – Chromosome Sudoku for Genetic Genealogy Addicts 
DNAPainter – Touring the Chromosome Garden 
DNAPainter – Mining Vendor Matches to Paint Your Chromosomes 
Proving or Disproving a Half Sibling Relationship Using DNAPainter

Combining the Two Tools

DNAPainter has the potential to really utilize the Leeds Method results, other than Ancestry matches of course. Ancestry does not provide segment information. (Yes, I know, dead horse but I still can’t resist an occasional whack.)

You’re going to utilize your spreadsheet groupings to paint the DNA from each individual match at the vendors to DNAPainter.

On the spreadsheet, if these matches are from Family Tree DNA, MyHeritage, 23andMe or GedMatch, you’ll copy the matching segments from that vendor and paint those matching segments at DNAPainter. I explained how to do that in the articles about DNAPainter.

I do not use mass uploads to DNAPainter, because it’s impossible to assign those to different sides of your tree or ancestors. I paint individual matches, including information about the match and what I know about the history of the segment itself or associated ancestor.

I only paint segments that I can identify with certainty as maternal or paternal.

Pushing Back in Time

Based on which segments of identified ancestors the Leeds matches overlap with at DNAPainter, I can push that segment information further back in time. The blessing of this is that these Leeds matches may well fill in several blanks in my chromosome that are not yet painted by people with whom I share identified ancestors.

Even if your maternal and paternal grandparents are intermarried on each side, as long as they are not intermarried across your parental lines (meaning mother & father,) then the Leeds Method will work fine for painting. Even if you think you are attributing a segment to your paternal grandmother, for example, and the person actually matches through your paternal grandfather, you’ve still painted them on the correct chromosome – meaning your paternal chromosome. As you build up that chromosome with matches, you’ll see soon enough if you have 9 matches attributed to John Doe and one to Jane Smith, the Jane Smith match is likely incorrectly attributed, those two lines are somehow interrelated or it’s a false positive match.

Because I work with only fairly large Leeds matches – nothing below 30 cM, I sometimes receive a nice gift in terms of painting large previously unpainted segments – like the one on my mother’s side, below.

Look at this large green segment on chromosome 19 that I painted thanks to one of the Leeds matches, Harold. (Note that the two long blue and brown bars at the bottom of each chromosome are my ethnicity, not matches.) Another benefit is that if a Leeds match matches on already identified segments assigned to ancestors, I’ve just identified which ancestral lines I share with that match.

The green Ferverda side match to Roland through the Leeds Method aligns partially with a segment already known to descend from Jacob Lentz and Frederica Ruhle who were born in the 1780s. I’m related to Roland somehow through that line, and by just looking at his (redacted here) surname, I *think* I know how, even though he doesn’t have a tree online. How cool is that!

Important Notes for DNAPainter

Word of caution here. I would NOT paint anyone who falls into multiple match groups without being able to identify ancestors. Multiple match groups may indicate multiple ancestors, even if you aren’t aware of that.

Each segment has its own history, so it’s entirely possible that multiple match groups are accurate. It’s also possible that to some extent, especially with smaller segments, that matches by chance come into play. That’s why I only work with segments above 30 cM when using the Leeds method where I know I’m safe from chance matches. You can read about identical by descent (IBD) and identical by chance (IBC) matches here.

What a DNAPainter Leeds Match Means

It’s very important to label segments in DNAPainter with the fact that the source was through the Leeds Method.

These painted matches DO NOT MEAN that the match descends from the grandparent you are associating with the match.

It means that YOU inherited your common DNA with this match FROM that grandparent. It suggests that your match descends from one of the ancestors of this couple, or possibly from your great-grandparents, but you don’t necessarily share this great-grandparent couple with your match.

That’s different than the way I normally paint my chromosomes – meaning only when a specific common ancestor has been identified. For someone painted from matches NOT identified through the Leeds Method, if I know the person descends from a grandparent, I paint them to the great-grandparent couple. People painted through the Leeds Method don’t necessarily share that couple, but do share an ancestor of that couple.

When I paint using the Leeds method, I’m assigning the match to a set of great-grandparents because I can’t genealogically identify the common ancestor further upstream, so I’m letting genetics tell me which genealogical quadrant they fall into on my tree. With the Leeds Method, I can tell which grandparent I inherited that DNA through. In my normal DNAPainter methodology, I ONLY paint matches when I’ve identified the common ancestor – so Leeds Method matches would not previously have qualified.

I don’t mean to beat this to death and explain it several ways – but it’s really important to understand the difference and when looking back, understand why you painted what you did.

Labeling Leeds Match Painted Segments

Therefore, with Leeds Method match painting, I identify the match name as “John Doe FTDNA Leeds-Ferverda” which tells me the matches name (John Doe,) where they tested (FTDNA) and why I painted them (Ferverda column in my Leeds spreadsheet,) even though I don’t know for sure which ancestor we actually have in common. I paint them to the parents of my Ferverda grandfather. Not John Ferverda, my grandfather, but to his parents, Hiram Ferverda and Eva Miller. I know I received my matching DNA through one of them – I just don’t know which person of that couple yet.

However, looking at who else is assigned to that segment with an identified common ancestor will tell me where in my tree that segment originated – for me. We still don’t know where in your matches tree that segment originated.

“Match To” Issues

Lastly, if you happen to select a “match to” person to represent one of your grandparent matches that just happens to be descended from two grandparent lines, you’ve had your bad luck for the month. Remember, your “match to” person is the first person (closest match) that hasn’t yet been grouped, so you don’t really select them. If you realize you’re getting goofy results, stop and undo those results, then select the next candidate as your “match to” person.

At one vendor, when I selected the first person who hadn’t yet been grouped and used them for the red column which turned out to be Bolton, about half of them overlapped with Estes segments that I’ve already painted and confirmed from several sources. Obviously, there’s a problem someplace, and I’m guessing it just happens to be the luck of the draw with the “match to” person being descended from both lines. The lines both lived in the same county for generations. I need to redo that section with someone whose tree I know positively descends from the Bolton line and does NOT intersect with another of my lines. However, I was able to identify that this issue existed because I’ve already painted multiple ancestor-confirmed cousins who carry those same segments – and I know where they came from.

These tools are just that – tools and require some level of analytical skill and common sense. In other words, it’s a good idea to stay with larger matches and know when to say “uh-oh.” If it doesn’t feel right, don’t paint it.

Breaking Down Distant Brick Walls

I’m still thinking about how to use the Leeds Method, probably in combination with DNAPainter, to break down brick walls. My brick walls aren’t close in time. Most of them are several generations back and revolve around missing female surnames, missing records or ancestors appearing in a new location with no ability to connect them back to the location/family they left.

In essence, I would need to be able to isolate the people matching that most distant ancestor couple, then look for common surnames and ancestors within that match group. The DNAGedcom.com client which allows you to sort matches by surname might well be an integral piece of this puzzle/solution. I’ll have to spend some time to see how well this works.

Solving this puzzle would be entirely dependent on people uploading their trees.

If you have thoughts on how to use these tools to break down distant brick walls, or devise a methodology, please let me know.

And if you haven’t uploaded your tree, please do.

Would I Do The Leeds Method Again?

Absolutely, at least for the vendors who provide segment information.

I painted 8 new Leeds matches from Family Tree DNA on my Ferverda grandparent side which increased the number of painted segments at DNAPainter from 689 to 704, filled in a significant number of blank spaces on my chromosomes, and took my total % DNA painted from 60 to 61%. I added the rest of my Leeds hints from Family Tree DNA of 30 cM or over, and increased my painted segments to 734 and my percentage to 62% I know that 1 or 2% doesn’t sound like a very big increase, but it’s scientific progress.

It’s more difficult to increase the number of new segments after you’ve painted much of your genome because many segments overlap segments already painted. So, a 2% increase is well worth celebrating!

Having said that, I would love for the vendors to provide this type of clustering so I don’t have to. To date, Family Tree DNA is the only vendor who does any flavor of automatically bucketing results in this fashion – meaning paternal and maternal, which is half the battle. I would like to see them expand to the four grandparents from the maternal/paternal matching they provide today.

We’ve been asking Ancestry for enhanced tools for years. There’s no reason they couldn’t in essence do what Dana has done along with provide the DNAgedcom.com search functionality. And yes…I still desperately want a chromosome browser or at least segment information.

I will continue to utilize the Leeds Method, at least with vendors other than Ancestry because it allows me to incorporate the results with DNAPainter. It’s somehow ironic that I started out grouping the Ancestry results, but wound up realizing that the results from other vendors, specifically Family Tree DNA and MyHeritage are significantly more useful due to the segment data and combined tools.

Getting the Most Bang for Your Buck

If you tested at Ancestry or 23andMe, I would strongly encourage you to download your raw data file from both of these vendors and transfer to Family Tree DNA, MyHeritage and GedMatch to get the most out of your DNA tests. Here is the step-by-step guide for how to download your DNA from Ancestry.

The uploads to those three locations are free. All tools are free at MyHeritage until December 1, 2018 when they will begin charging for more advanced tools. The upload is free at Family Tree DNA and the advanced tools, including the chromosome browser, only require a $19 unlock.

Here is the step-by-step guide for uploading to MyHeritage and to Family Tree DNA. Fishing in every pond is critically important. You never know what you’re missing otherwise!

How many segments of your DNA can you paint using the Leeds Method in combination with DNA Painter?

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Services

Genealogy Research

The Leeds Method

This is the first in a series of two articles. This article explains the Leeds Method and how I created a Leeds Spreadsheet in preparation for utilizing the results in DNAPainter. I stumbled around a bit, but I think I’ve found a nice happy medium and you can benefit from my false starts by not having to stumble around in the dark yourself. Of course, I’m telling you about the pitfalls I discovered.

The second article details the methodology I utilized to paint these matches, because they aren’t quite the same as “normal” matching segments with identified ancestors.

Welcome to the Leeds Method

Dana Leeds developed a novel way to utilize a spreadsheet for grouping your matches from second through fourth cousins and to assign them to “grandparent” quadrants with no additional or previous information. That’s right, this method generates groupings that can be considered good hints without any other information at all.

Needless to say, this is great for adoptees and those searching for a parent.

It’s also quite interesting for genetic genealogists as well. One of the best aspects is that it’s very easy to do and very visual. Translation – no math. No subtraction.

Caveat – it’s also not completely accurate 100% of the time, especially when you are dealing with more distant matches, intermarriage and/or endogamy. But there are ways to work around these issues, so read on!

You can click to enlarge any image.

I’ll be referring to this graphic throughout this article. It shows the first several people on my Ancestry match list, beginning with second cousins, using pseudonyms. I chose to use Ancestry initially because they don’t provide chromosome browsers or triangulation tools, so we need as much help there as we can get.

I’ve shown the surnames of my 4 grandparents in the header columns with an assigned color, plus a “Weird group” (grey) that doesn’t seem to map to any of the 4. People in that group are much more distant in my match list, so they aren’t shown here.

I list the known “Most Common Recent Ancestor,” when identified, along with the color code that so I can easily see who’s who.

All those blanks in the MCRA column – those are mostly people without trees. Just think how useful this would be if everyone who could provide a tree did!

What Does the Leeds Method Tell You?

The Leeds Method divides your matches into four colored quadrants representing each grandparent unless your genealogical lines are heavily intermarried. If you have lots of people who fall into both of two (or more) colors, that probably indicates intermarriage or a heavily endogamous population.

In order to create this chart, you work with your closest matches that are 2nd cousins or more distant, but no more distant than 4th cousins. For endogamous people, by the time you’re working in 4th cousins, you’ll have too much overlap, meaning people who fall into multiple columns, so you’ll want to work with primarily 2nd and 3rd cousins. The good news is that endogamous people tend to have lots of matches, so you should still have plenty to work with!

Instructions

In this article, I’m using Dana’s method, with a few modifications.

By way of a very, very brief summary:

  • On a spreadsheet, you list all of your matches through at least third cousins
  • Then check each match to see who you match in common with them
  • Color code the results, in columns
  • Each person what you match in common with your closest cousin, Sleepy, is marked as yellow. Dopey and I both match Bashful and Jasmine in common and are colored Red. Doc and I both match Happy and Belle and are colored blue, and so forth.
  • The result is that each color represents a grandparent

To understand exactly what I’m doing, read Dana’s articles, then continue with this article.

DNA Color Clustering: The Leeds Method for Easily Visualizing Matches  
DNA Color Clustering: Identifying “In Common” Surnames 
DNA Color Clustering: Does it Work with 4th Cousins? By the way, yes it does, most of the time.
DNA Color Clustering: Dealing with 3 Types of Overlap

Why Use “The Leeds Method”?

In my case, I wanted to experiment. I wanted to see if this method works reliably and what could be done with the information if you already know a significant amount about your genealogy. And if you don’t.

The Leeds Method is a wonderful way to group people into 4 “grandparent” groups in order to search for in-common surnames. I love being able to perform this proof of concept “blind,” then knowing my genealogy and family connections well enough to be able to ascertain whether it did or didn’t work accurately.

If you can associate a match with a single grandparent, that really means you’ve pushed that match back to the great-grandparent couple.

That’s a lot of information without any genealogical knowledge in advance.

How Low Can You Go?

I have more than 1000 fourth cousins at Ancestry. This makes the task of performing the Leeds Method manually burdensome at that level. It means I would have had to type all 1000+ fourth cousins into a spreadsheet. I’m patient, but not that patient, at least not without a lot of return for the investment. I have to ask myself, exactly what would I DO with that information once they were grouped?

Would 4th cousin groupings provide me with additional information that second and third cousin groupings wouldn’t? I don’t think so, but you can be the judge.

After experimenting, I’d recommend creating a spreadsheet listing all of your 2nd and 3rd cousins, along with about 300 or so of your closest 4th cousin matches. Said another way, my results started getting somewhat unpredictable at about 40-45 cMs, although that might not hold true for others. (No, you can’t tell the longest matching segment length at Ancestry, but I could occasionally verify at the other vendors, especially when people from Ancestry have transferred.)

Therefore, I only proceeded through third cousins and about 300 of the Ancestry top 4th cousin matches.

I didn’t just utilize this methodology with Ancestry, but with Family Tree DNA, MyHeritage and 23andMe as well. I didn’t use GedMatch because those matches would probably have tested at one of the primary 4 vendors and I really didn’t want to deal with duplicate kits any more than I already had to. Furthermore, GedMatch is undergoing a transition to their Genesis platform and matching within the Genesis framework has yet to be perfected for kits other than those from these vendors.

Let’s talk about working with matches from each vendor.

Ancestry

At Ancestry, make a list of all of your second and third cousin matches, plus as many 4th cousins as you want to work with.

To begin viewing your common matches, select your first second cousin on the list and click on the green View Match. (Note that I am using my own second kit at Ancestry, RobertaV2Estes, not a cousin’s kit in these examples. The methodology is the same, so don’t fret about that.)

Then, click on Shared Matches.

Referring to your spreadsheet, assign a color to this match group and color the spreadsheet squares for this match group. Looking at my spreadsheet, my first group would be the yellow Estes group, so I color the squares for each person that I match in common with this particular cousin. On my spreadsheet, those cousins have all been assigned pseudonyms, of course.

Your shared match list will be listed in highest match order which should be approximately the same order they are listed on your spreadsheet. I use two monitors so I can display the spreadsheet on one and the Ancestry match list on the other.

Lon is shared in common with the gold person I’m comparing against (Roberta V2 Estes), and me, so his box would be colored gold on the spreadsheet. Lon’s pseudonym is Sneezy and the person beneath him on this list, not shown, would be Ariel.

Ancestry only shows in-common matches to the 4th cousin level, so you really couldn’t reach deeper if you wanted. Furthermore, I can’t see any advantage to working beyond the 4th cousin’s level, maximum. Your best matches are going to be the largest ones that reveal the most information and have the most matches, therefore allowing you to group the most people by color.

Unfortunately, Ancestry provides the total cMs and the number of segments, but not the largest matching segment.

One benefit of this methodology is that it’s fairly easy to group those pesky private matches like the last one on the master spreadsheet, Cersei, shown in red. You’ll at least know which grandparent group they match. Based on your identified ancestors of matches in the color group, you may be able to tell much more about that private match.

For example, one of my private matches is a match to someone who I share great-great-grandparents with AND they also match with two people further on up that tree on the maternal side of that couple, shown above, in red. I may never know which ancestor I share with that private match specifically, but I have a pretty darned good idea now in spite of that ugly little lock. The more identified matches, the better and more accurate this technique.

Is the Leeds Method foolproof? No.

Is this a great tool? Yes, absolutely.

Family Tree DNA

Thankfully, Family Tree DNA provides more information about my matches than Ancestry, including segment information combined with a chromosome browser and Family Matching. I often refer to Family Matching as parental bucketing, shown on your match list with the maternal and paternal tabs, because Family Tree DNA separates your matches into parental “sides” based on common segments with others on your maternal and paternal branches of your tree when you link your matches’ results.

At Family Tree DNA, sign on and then click on Matches under Family Finder.

When viewing your matches, you’ll see blue or red people icons any that are assigned to either your maternal, paternal side, or both (purple) on your match list. If you click on the tabs at the top,  you’ll see JUST the maternal, paternal or both lists.

This combination of tools allows you to confirm (and often triangulate) the match for several people. If those matches are bucketed, meaning assigned to the same parental side, and they match on the same segment, they are triangulated for all intents and purposes if the segment is above 20 cM. All of the matches I worked with for the Leeds Method were well above 20 cM, so you don’t really need to worry about false or identical by chance matches at that level.

Family Tree DNA matches are initially displayed by the total number of “Shared cM.” Click on “Longest Block” to sort in that manner. I considered people through 30 cM and above as equivalent to the Ancestry 3rd cousin category. Some of the matching became inconsistent below that threshold.

List all of your second and third cousins on the spreadsheet, along with however many 4th cousins you want to work with.

Then, select your closest second cousin by checking the box to the left of that individual, then click on “In Common With” above the display. This shows you your matches in common with this person.

On the resulting common match list, sort your matches in Longest block order, then mark the matches on your spreadsheet in the correct colored columns.

With each vendor, you may need to make new columns until you can work with enough matches to figure out which column is which color – then you can transfer them over. If you’re lucky enough to already know the family association of your closest cousins, then you already know which colored column they belong to.

All of my matches that fell into the Leeds groups were previously bucketed to maternal or paternal, so consistency between the two confirms both methodologies. Between 20 and 28 cM, three of my bucketed matches at Family Tree DNA fell into another group using the Leeds method, which is why I drew the line at 30cM.

For genealogists who already know a lot about their tree, this methodology in essence divides the maternal and paternal buckets into half. FTDNA already assigns matches maternally or paternally with Family Matching if you have any information about how your matches fit into your tree and can link any matching testers to either side of your tree at the 3rd cousin level or closer.

If you don’t know anything about your heritage, or don’t have any way to link to other family members who have tested, you’ll start from scratch with the Leeds Method. If you can link family members, Family Tree DNA already does half of the heavy lifting for you which allows you to confirm the Leeds methodology.

MyHeritage

At MyHeritage, sign in, click on DNA and sort by “largest segment,” shown at right, above. I didn’t utilize matches below 40 cM due to consistency issues. I wonder if imputation affects smaller matches more than larger matches.

You’ll see your closest matches at the top of the page. Scroll down and make a list on your spreadsheet of your second and third cousins. Return to your closest DNA match that is a second cousin and click on the purple “Review DNA Match” which will display your closest in-common matches with that person, but not necessarily in segment size order.

Scroll down to view the various matches and record on the spreadsheet in their proper column by coloring that space.

The great aspect of MyHeritage is that triangulation is built in, and you can easily see which matches triangulate, providing another layer of confirmation, assuming you know the relationship of at least some of your matches.

The message for me personally at MyHeritage is that I need to ask known cousins who are matches elsewhere to upload to MyHeritage because I can use those as a measuring stick to group matches, given that I know the cousin’s genealogy hands-down.

The great thing about MyHeritage is that they are focused on Europe, and I’m seeing European matches that aren’t anyplace else.

23andMe

At 23andMe, sign in and click on DNA Relatives under the Ancestry tab.

You’ll see your list of DNA matches. Record 2nd and third cousins on your spreadsheet, as before.

To see who you share in common with a match, click on the person’s name and color your matches on the spreadsheet in the proper column.

Unfortunately, the Leeds Method simply didn’t work well for me with my 23andMe data, or at least the results are highly suspect and I have no way of confirming accuracy.

Most of my matches fell into in the Estes category, with the Boltons overlapping almost entirely, and none in the Lore or Ferverda columns. There is one small group that I can’t identify. Without trees or surnames, genealogically, my hands are pretty much tied. I can’t really explain why this worked so poorly at 23andMe. Your experience may be different.

The lack of trees is a significant detriment at 23andMe because other than a very few matches whose genealogy I know, there’s no way to correlate or confirm accuracy. My cousins who tested at 23andMe years ago and whose tests I paid for lost interest and never signed in to re-authorize matching. Many of those tests are on the missing Ferverda side, but their usefulness is now forever lost to me.

23andMe frustrates me terribly. Their lack of commitment to and investment in the genealogical community makes working with their results much more difficult than it needs to be. I’ve pretty much given up on using 23andMe for anything except adoption searches for very close matches as a last resort, and ethnicity.

The good news is that with so many people testing elsewhere, there’s a lot of good data just waiting!

What are the Benefits?

The perception of “benefit” is probably directly connected to your goal for DNA testing and genetic genealogy.

  • For adoptees or people seeking unknown parentage or unknown grandparents, the Leeds Method is a fantastic tool, paving the way to search for common surnames within the 4 groups as opposed to one big pool.
  • For people who have been working with their genealogy for a long time, maybe not as much, but hints may lurk and you won’t know unless you do the discovery work. If you’re a long-time genealogist, you’re used to this, so it’s just a new way of digging through records – and you can do it at home!
  • For people who have tested at Family Tree DNA, the family grouping by maternal and paternal based on people linked to your tree is more accurate and groups people further down your match list because it’s actually based on triangulated matching segments. However, the Leeds Method expands on that and adds granularity by breaking those two groups into four.
  • For people who want to paint their chromosomes using DNAPainter, the Leeds Method is the first step of a wonderful opportunity if you have tested at either Family Tree DNA, MyHeritage or 23andMe.

Unfortunately, Ancestry doesn’t provide segment information, so you can’t chromosome paint from Ancestry directly, BUT, you can upload to either Family Tree DNA, MyHeritage or GedMatch and paint Ancestry matches from there. At GedMatch, their kit numbers begin with A.

What Did I Do Differently than Dana?

Instead of adding a 5th column with the first person (Sam) who was not grouped into the first 4 groups, I looked for the closest matches that I shared with Sam who were indeed in the first 4 color groups. I added Sam to that existing color group along with my shared matches with Sam that weren’t already grouped into that color so long as it was relatively consistent. If it looked too messy, meaning I found people in multiple match groups, I left it blank or set that match aside. This didn’t happen until I was working at the 4th cousin level or between 30 and 40 cM, depending on the vendor.

Please note that just because you find people that you match in common with someone does NOT MEAN that you all share a common ancestor, or the same ancestor. It’s a hint, a tip to be followed.

There were a couple of groups that I couldn’t cluster with other groups, and one match that clustered in three of the four grandparent groups. I set that one aside as an outlier. I will attempt to contact them. They don’t have a tree.

I grouped every person through third cousin matches. I started out manually adding the 4th cousins for each match, but soon gave up on that due to the sheer magnitude. I did group my closest 4th cousins, or until they began to be inaccurate or messy, meaning matching in multiple groups. Second and third cousin matching was very consistent.

Tips

  • Don’t use siblings or anyone closer than the second cousin level. First cousins share two grandparents. You only want to use matches that can be assigned to ONLY ONE GRANDPARENT.
  • In the spreadsheet cell, mark the person you used as a “match to.” In other words, which people did you use to populate that color group. You can see that I used two different people in the Estes category. I used more in the other categories too, but they are further down in my list.
  • At Family Tree DNA, you can utilize the X chromosome. Understand that if you are a male, you will not have any X matches with your paternal grandfather. I would not recommend using X matches for the Leeds Method, especially since they are not uniformly available at all vendors and form a specific unique inheritance pattern that is not the same as the other autosomes.
  • Ancestry, MyHeritage and Family Tree DNA allow you to make notes on each match. As I group these, and as I paint them with DNAPainter I made a note on each match that allows me to identify which group they are assigned to, or if they match multiple groups.
  • Look at each match to be sure they are consistent. If they aren’t, either mark them as inconclusive or omit them entirely in the painting process. I write notes on each one if there is something odd, or if I don’t paint them.

What Did I Learn?

Almost all of my (endogamous by definition) Acadian matches are more distant, which means the segments are smaller. I expected to find more in the painted group, because I have SO MANY Acadian matches, but given that my closest Acadian ancestor was my great-great-grandfather, those segments are now small enough that those matches don’t appear in the candidate group of matches for the Leeds Method. My Acadian heritage occurs in my green Lore line, and there are surprisingly few matches in that grouping large or strong enough to show up in my clustered matches. In part, that’s probably because my other set of great-great-grandparents in that line arrived in 1852 from Germany and there are very few people in the US descended from them.

I found 4th cousin matches I would have otherwise never noticed because they don’t have a tree attached. At Ancestry, I only pay attention to closer matches, Shared Ancestor Hints and people with trees. We have so many matches today that I tend to ignore the rest.

Based on the person’s surname and the color group into which they fall, it’s often possible to assign them to a probable ancestral group based on the most distant ancestors of the people they match within the color group. In some cases, the surname is another piece of evidence and may provide a Y DNA lead.

For example, one of my matches user name is XXXFervida. They do match in the Ferverda grandparent group, and Fervida is how one specific line of the family spelled the surname. Of course, I could have determined that without grouping, but you can never presume a specific connection based solely on surname, especially with a more common name. For all I know, Fervida could be a married name.

By far the majority of my matches don’t have trees or have very small trees. That “no-tree” percentage is steadily increasing at Ancestry, probably due to their advertising push for ethnicity testing. At Family Tree DNA where trees are infinitely more useful, the percentage of people WITH trees is actually rising. By and large, Family Tree DNA users tend to be the more serious genealogists.

MyHeritage launched their product more recently with DNA plus trees from the beginning, although many of the new transfers don’t have trees or have private trees. Their customers seem to be genealogically savvy and many live in Europe where MyHeritage DNA testing is focused.

23andMe is unquestionably the least useful for the Leeds Method because of their lack of support for trees, among other issues, but you may still find some gems there.

Keeping Current

Now that I invested in all of this work, how will I keep the spreadsheet current, or will I at all?

At Ancestry, I plan to periodically map all of my SAH (Shared Ancestor Hints) green leaf matches as well as all new second and third cousin matches, trees or not.

In essence, for those with DNA matches and trees with a common ancestor, Ancestry already provides Circles, so they are doing the grouping for those people. Where this falls short, of course, is matches without trees and without a common identified ancestor.

For Ancestry matches, I would be better served, I think, to utilize Ancestry matches at GedMatch instead of at Ancestry, because GedMatch provides segment information which means the matches can be confirmed and triangulated, and can be painted.

For matches outside of Ancestry, in particular at Family Tree DNA and MyHeritage I will keep the spreadsheet current at least until I manage to paint my entire set of chromosomes. That will probably be a very long time!

I may not bother with 23andMe directly, given that I have almost no ability to confirm accuracy. I will utilize 23andMe matches at GedMatch. People who transfer to GedMatch tend to be interested in genealogy.

What Else Can I Do?

At Ancestry, I can use Blaine’s new “DNA Match Labeling” tool that facilitates adding 8 colored tags to sort matches at Ancestry. Think of it as organizing your closet of matches. I could tag each of these matches to their grandparent side which would make them easy to quickly identify by this “Leeds Tag.”

My Goals

I have two primary goals:

  • Associating segments of my DNA with specific ancestors
  • Breaking down genealogical brick walls

I want to map my DNA segments to specific ancestors. I am already doing this using Family Tree DNA and MyHeritage where common ancestors are indicated in trees and by surnames. I can map these additional Leeds leads (pardon the pun) to grandparents utilizing this methodology.

To the extent I can identify paternal and maternal matches at 23andMe, I can do the same thing. I don’t have either parents’ DNA there, and few known relatives, so separating matches into maternal and paternal is more difficult. It’s not impossible but it means I can associate fewer matches with “sides” of my genealogy.

For associating segments with specific ancestors and painting my chromosomes, DNAPainter is my favorite tool.

In my next article, we’ll see how to use our Leeds Method results successfully with DNAPainter and how to interpret the results.

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