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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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

Genealogy Research

Fun DNA Stuff

  • Celebrate DNA – customized DNA themed t-shirts, bags and other items

Triangulation in Action at 23andMe

Recently, I published the article, Hitting a Genealogy Home Run Using Your Double-Sided Two-Faced Chromosomes While Avoiding Imposters. The “Home Run” article explains why you want to use a chromosome browser, what you’re seeing and what it means to you.

This article, and the rest in the “Triangulation in Action” series introduces triangulation at FamilyTreeDNA, MyHeritage, 23andMe, GedMatch and DNAPainter, explaining how to use triangulation to confirm descent from a common ancestor. You may want to read the introductory article first.

This first section, “What is Triangulation” is a generic tutorial. If you don’t need the tutorial, skip to the “Triangulation at 23andMe” section.

What is Triangulation?

Think of triangulation as a three-legged stool – a triangle. Triangulation requires three things:

  1. At least three (not closely related) people must match
  2. On the same reasonably sized segment of DNA and
  3. Descend from a common ancestor

Triangulation is the foundation of confirming descent from a common ancestor, and thereby assigning a specific segment to that ancestor. Without triangulation, you might just have a match to someone else by chance. You can confirm mathematical triangulation, numbers 1 and 2, above, without knowing the identity of the common ancestor.

Reasonably sized segments are generally considered to be 7cM or above on chromosomes 1-22 and 15cM or above for the X chromosome.

Boundaries

Triangulation means that all three, or more, people much match on a common segment. However, what you’re likely to see is that some people don’t match on the entire segment, meaning more or less than others as demonstrated in the following examples.

FTDNA Triangulation boundaries

You can see that I match 5 different cousins who I know descend from my father’s side on chromosome 15 above. “I” am the grey background against which everyone else is being compared.

I triangulate with these matches in different ways, forming multiple triangulation groups that I’ve discussed individually, below.

Triangulation Group 1

FTDNA triangulation 1

Group 1 – On the left group of matches, above, I triangulate with the blue, red and orange person on the amount of DNA that is common between all of them, shown in the black box. This is triangulation group 1.

Triangulation Group 2

FTDNA triangulation 2

Group 2 – However, if you look just at the blue and orange triangulated matches bracketed in green, I triangulate on slightly more. This group excludes the red person because their beginning point is not the same, or even close. This is triangulation group 2.

Triangulation Group 3 and 4

FTDNA triang 3

Group 3 – In the right group of matches, there are two large triangulation groups. Triangulation group 3 includes the common portions of blue, red, teal and orange matches.

Group 4 – Triangulation group 4 is the skinny group at right and includes the common portion of the blue, teal and dark blue matches.

Triangulation Groups 5 and 6

FTDNA triang 5

Group 5 – There are also two more triangulation groups. The larger green bracketed group includes only the blue and teal people because their end locations are to the right of the end locations of the red and orange matches. This is triangulation group 5.

Group 6 – The smaller green bracketed group includes only the blue and teal person because their start locations are before the dark blue person. This is triangulation group 6.

There’s actually one more triangulation group. Can you see it?

Triangulation Group 7

FTDNA triang 7

Group 7 – The tan group includes the red, teal and orange matches but only the areas where they all overlap. This excludes the top blue match because their start location is different. Triangulation group 7 only extends to the end of the red and orange matches, because those are the same locations, while the teal match extends further to the right. That extension is excluded, of course.

Slight Variations

Matches with only slight start and end differences are probably descended from the same ancestor, but we can’t say that for sure (at this point) so we only include actual mathematically matching segments in a triangulation group.

You can see that triangulation groups often overlap because group members share more or less DNA with each other. Normally we don’t bother to number the groups – we just look at the alignment. I numbered them for illustration purposes.

Shared or In-Common-With Matching

Triangulation is not the same thing as a 3-way shared “in-common-with” match. You may share DNA with those two people, but on entirely different segments from entirely different ancestors. If those other two people match each other, it can be on a segment where you don’t match either of them, and thanks to an ancestor that they share who isn’t in your line at all. Shared matches are a great hint, especially in addition to other information, but shared matches don’t necessarily mean triangulation although it’s a great place to start looking.

I have shared matches where I match one person on my maternal side, one on my paternal side, and they match each other through a completely different ancestor on an entirely different segment. However, we don’t triangulate because we don’t all match each other on the SAME segment of DNA. Yes, it can be confusing.

Just remember, each of your segments, and matches, has its own individual history.

Imputation Can Affect Matching

Over the years the chips on which our DNA is processed at the vendors have changed. Each new generation of chips tests a different number of markers, and sometimes different markers – with the overlaps between the entire suite of chips being less than optimal.

I can verify that most vendors use imputation to level the playing field, and even though two vendors have never verified that fact, I’m relatively certain that they all do. That’s the only way they could match to their own prior “only somewhat compatible” chip versions.

The net-net of this is that you may see some differences in matching segments at different vendors, even when you’re comparing the same people. Imputation generally “fills in the blanks,” but doesn’t create large swatches of non-existent DNA. I wrote about the concept of imputation here.

What I’d like for you to take away from this discussion is to be focused on the big picture – if and how people triangulate which is the function important to genealogy. Not if the start and end segments are exactly the same.

Triangulation Solutions

Each of the major vendors, except Ancestry who does not have a chromosome browser, offers some type of triangulation solution, so let’s look at what each vendor offers. If you and your Ancestry matches have uploaded to GedMatch, Family Tree DNA or MyHeritage, you can triangulate with them there. Otherwise, you can’t triangulate Ancestry results, so encourage your Ancestry matches to transfer.

I wrote more specifically about triangulation here and here.

Let’s look at triangulation at 23andMe.

Triangulation at 23andMe

At 23andMe, click on “DNA Relatives” in the Ancestry dropdown at the top of your page.

Triangulation 23andMe DNA Relatives.png

You will then see your list of matches.

23andMe does offer a Mom’s side and Dad’s side option, but only if at least one of your parents has tested AND you and that parent BOTH elect to share with each other. It’s not automatic.

To view your relationship with someone on your match list, click on that person’s name. I selected a known relative on my father’s side, Stacy.

Scroll down to the “Relatives in Common” section where you will see your matches in common with the person you selected. Stacy and I have 284 matches in common.

Triangulation 23andMe shared DNA.png

You can view the relationships of the match to you, and also to the person you’ve selected.

“Yes,” in the shared DNA column indicates that you, the person you selected (Stacy) and this match share DNA on a common segment. In other words, you triangulate.

In this example, Stacy and I share a triangulated segment with my own V4 kit (of course), and with both James and Diana, but not with George or Everett. We both match James and Everett, just not on the same segment, so we don’t triangulate.

Let’s look at James. By clicking on “Yes,” I can view the chromosome browser.

Scrolling down, I see that Stacy (purple), me (background grey) and James (orange) share DNA on only one segment, on chromosome 17.

Triangulation 23andMe chromosome 17.png

That segment triangulates between the three of us. I know how I am related to Stacy, but not how I am related to James. I can tell via my matches and triangulation with James that our common segment descends to me through my Vannoy line.

Unfortunately, 23andMe does not support trees in the traditional way, but some people enter surnames and locations, and you can download some Family Search ancestors to 23andMe or place a link to a tree elsewhere. I wrote about that here.

Check your 23andMe matches for surnames, common locations and links to trees.

You can also download your 23andMe segment matches and their information by clicking on Download Aggregate Data at the bottom of your matches page. Segment matches tell you exactly where on each chromosome you match other people.

Triangulation 23andMe download.png

Segment matches is NOT the same thing as downloading your raw DNA data file to upload to another vendor. See the Transfer section for those instructions.

Other 23andMe Resources to Identify Common Ancestors

23andMe provides additional tools, noted below, with the links to instructional articles I’ve written.

Transfers

Have you tested family members, especially everyone in the older generations? You can transfer their kits from Ancestry or 23andMe if they have already tested there to MyHeritage, FamilyTreeDNA or GedMatch.

Here’s how to transfer:

I wrote recently about how to work with triangulation at FamilyTreeDNA. and MyHeritage. Join me soon for similar articles about how to work with triangulation at GedMatch and DNAPainter.

Most of all – 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

Genealogy Research

Fun DNA Stuff

  • Celebrate DNA – customized DNA themed t-shirts, bags and other items

2019: The Year and Decade of Change

2019 ends both a year and a decade. In the genealogy and genetic genealogy world, the overwhelmingly appropriate word to define both is “change.”

Everything has changed.

Millions more records are online now than ever before, both through the Big 3, being FamilySearch, MyHeritage and Ancestry, but also through multitudes of other sites preserving our history. Everyplace from National Archives to individual blogs celebrating history and ancestors.

All you need to do is google to find more than ever before.

I don’t know about you, but I’ve made more progress in the past decade that in all of the previous ones combined.

Just Beginning?

If you’re just beginning with genetic genealogy, welcome! I wrote this article just for you to see what to expect when your DNA results are returned.

If you’ve been working with genetic genealogy results for some time, or would like a great review of the landscape, let’s take this opportunity to take a look at how far we’ve come in the past year and decade.

It’s been quite a ride!

What Has Changed?

EVERYTHING

Literally.

A decade ago, we had Y and mitochondrial DNA, but just the beginning of the autosomal revolution in the genetic genealogy space.

In 2010, Family Tree DNA had been in business for a decade and offered both Y and mitochondrial DNA testing.

Ancestry offered a similar Y and mtDNA product, but not entirely the same markers, nor full sequence mitochondrial. Ancestry subsequently discontinued that testing and destroyed the matching database. Ancestry bought the Sorenson database that included Y, mitochondrial and autosomal, then destroyed that data base too.

23andMe was founded in 2006 and began autosomal testing in 2007 for health and genealogy. Genealogists piled on that bandwagon.

Family Tree DNA added autosomal to their menu in 2010, but Ancestry didn’t offer an autosomal product until 2012 and MyHeritage not until 2016. Both Ancestry and MyHeritage have launched massive marketing and ad campaigns to help people figure out “who they are,” and who their ancestors were too.

Family Tree DNA

2019 FTDNA

Family Tree DNA had a banner year with the Big Y-700 product, adding over 211,000 Y DNA SNPs in 2019 alone to total more than 438,000 by year end, many of which became newly defined haplogroups. You can read more here. Additionally, Family Tree DNA introduced the Block Tree and public Y and public mitochondrial DNA trees.

Anyone who ignores Y DNA testing does so at their own peril. Information produced by Y DNA testing (and for that matter, mitochondrial too) cannot be obtained any other way. I wrote about utilizing mitochondrial DNA here and a series about how to utilize Y DNA begins in a few days.

Family Tree DNA remains the premier commercial testing company to offer high resolution and full sequence testing and matching, which of course is the key to finding genealogy solutions.

In the autosomal space, Family Tree DNA is the only testing company to provide Phased Family Matching which uses your matches on both sides of your tree, assuming you link 3rd cousins or closer, to assign other testers to specific parental sides of your tree.

Family Tree DNA accepts free uploads from other testing companies with the unlock for advanced features only $19. You can read about that here and here.

MyHeritage

MyHeritage, the DNA testing dark horse, has come from behind from their late entry into the field in 2016 with focused Europeans ads and the purchase of Promethease in 2019. Their database stands at 3.7 million, not as many as either Ancestry or 23andMe, but for many people, including me – MyHeritage is much more useful, especially for my European lines. Not only is MyHeritage a genealogy company, piloted by Gilad Japhet, a passionate genealogist, but they have introduced easy-to-use advanced tools for consumers during 2019 to take the functionality lead in autosomal DNA.

2019 MyHeritage.png

You can read more about MyHeritage and their 2019 accomplishments, here.

As far as I’m concerned, the MyHeritage bases-loaded 4-product “Home Run” makes MyHeritage the best solution for genetic genealogy via either testing or transfer:

  • Triangulation – shows testers where 3 or more people match each other. You can read more, here.
  • Tree Matching – SmartMatching for both DNA testers and those who have not DNA tested
  • Theories of Family Relativity – a wonderful new tool introduced in February. You can read more here.
  • AutoClusters – Integrated cluster technology helps you to visualize which groups of people match each other.

One of their best features, Theories of Family Relativity connects the dots between people you DNA match with disparate trees and other documents, such as census. This helps you and others break down long-standing brick walls. You can read more, here.

MyHeritage encourages uploads from other testing companies with basic functions such as matching for free. Advanced features cost either a one-time unlock fee of $29 or are included with a full subscription which you can try for free, here. You can read about what is free and what isn’t, here.

You can develop a testing and upload strategy along with finding instructions for how to upload here and here.

23andMe

Today, 23andMe is best known for health, having recovered after having had their wings clipped a few years back by the FDA. They were the first to offer Health results, leveraging the genealogy marketspace to attract testers, but have recently been eclipsed by both Family Tree DNA with their high end full Exome Tovana test and MyHeritage with their Health upgrade which provides more information than 23andMe along with free genetic counseling if appropriate. Both the Family Tree DNA and MyHeritage tests are medically supervised, so can deliver more results.

23andMe has never fully embraced genetic genealogy by adding the ability to upload and compare trees. In 2019, they introduced a beta function to attempt to create a genetic tree on your behalf based on how your matches match you and each other.

2019 23andMe.png

These trees aren’t accurate today, nor are they deep, but they are a beginning – especially considering that they are not based on existing trees. You can read more here.

The best 23andMe feature for genealogy, as far as I’m concerned, is their ethnicity along with the fact that they actually provide testers with the locations of their ethnicity segments which can help testers immensely, especially with minority ancestry matching. You can read about how to do this for yourself, here.

23andMe generally does not allow uploads, probably because they need people to test on their custom-designed medical chip. Very rarely, once that I know of in 2018, they do allow uploads – but in the past, uploaders do not receive all of the genealogy features and benefits of testing.

You can however, download your DNA file from 23andMe and upload elsewhere, with instructions here.

Ancestry

Ancestry is widely known for their ethnicity ads which are extremely effective in recruiting new testers. That’s the great news. The results are frustrating to seasoned genealogists who get to deal with the fallout of confused people trying to figure out why their results don’t match their expectations and family stories. That’s the not-so-great news.

However, with more than 15 million testers, many of whom DO have genealogy trees, a serious genealogist can’t *NOT* test at Ancestry. Testers do need to be aware that not all features are available to DNA testers who don’t also subscribe to Ancestry’s genealogy subscriptions. For example, you can’t see your matches’ trees beyond a 5 generation preview without a subscription. You can read more about what you do and don’t receive, here.

Ancestry is the only one of the major companies that doesn’t provide a chromosome browser, despite pleas for years to do so, but they do provide ThruLines that show you other testers who match your DNA and show a common ancestor with you in their trees.

2019 Ancestry.png

ThruLines will also link partial trees – showing you ancestral descendants from the perspective of the ancestor in question, shown above. You can read about ThruLines, here.

Of course, without a chromosome browser, this match is only as good as the associated trees, and there is no way to prove the genealogical connection. It’s possible to all be wrong together, or to be related to some people through a completely different ancestor. Third party tools like Genetic Affairs and cluster technology help resolve these types of issues. You can read more, here.

You can’t upload DNA files from other testing companies to Ancestry, probably due to their custom medical chip. You can download your file from Ancestry and upload to other locations, with instructions here.

Selling Customers’ DNA

Neither Family Tree DNA, MyHeritage nor Gedmatch sell, lease or otherwise share their customers’ DNA, and all three state (minimally) they will not in the future without prior authorization.

All companies utilize their customers’ DNA internally to enhance and improve their products. That’s perfectly normal.

Both Ancestry and 23andMe sell consumers DNA to both known and unknown partners if customers opt-in to additional research. That’s the purpose of all those questions.

If you do agree or opt-in, and for those who tested prior to when the opt-in began, consumers don’t know who their DNA has been sold to, where it is or for what purposes it’s being utilized. Although anonymized (pseudonymized) before sale, autosomal results can easily be identified to the originating tester (if someone were inclined to do so) as demonstrated by adoptees identifying parents and law enforcement identifying both long deceased remains and criminal perpetrators of violent crimes. You can read more about re-identification here, although keep in mind that the re-identification frequency (%) would be much higher now than it was in 2018.

People are widely split on this issue. Whatever you decide, to opt-in or not, just be sure to do your homework first.

Always read the terms and conditions fully and carefully of anything having to do with genetics.

Genealogy

The bottom line to genetic genealogy is the genealogy aspect. Genealogists want to confirm ancestors and discover more about those ancestors. Some information can only be discovered via DNA testing today, distant Native heritage, for example, breaking through brick walls.

This technology, as it has advanced and more people have tested, has been a godsend for genealogists. The same techniques have allowed other people to locate unknown parents, grandparents and close relatives.

Adoptees

Not only are genealogists identifying people long in the past that are their ancestors, but adoptees and those seeking unknown parents are making discoveries much closer to home. MyHeritage has twice provided thousands of free DNA tests via their DNAQuest program to adoptees seeking their biological family with some amazing results.

The difference between genealogy, which looks back in time several generations, and parent or grand-parent searches is that unknown-parent searches use matches to come forward in time to identify parents, not backwards in time to identify distant ancestors in common.

Adoptee matching is about identifying descendants in common. According to Erlich et al in an October 2018 paper, here, about 60% of people with European ancestry could be identified. With the database growth since that time, that percentage has risen, I’m sure.

You can read more about the adoption search technique and how it is used, here.

Adoptee searches have spawned their own subculture of sorts, with researchers and search angels that specialize in making these connections. Do be aware that while many reunions are joyful, not all discoveries are positively received and the revelations can be traumatic for all parties involved.

There’s ying and yang involved, of course, and the exact same techniques used for identifying biological parents are also used to identify cold-case deceased victims of crime as well as violent criminals, meaning rapists and murderers.

Crimes Solved

The use of genetic genealogy and adoptee search techniques for identifying skeletal remains of crime victims, as well as identifying criminals in order that they can be arrested and removed from the population has resulted in a huge chasm and division in the genetic genealogy community.

These same issues have become popular topics in the press, often authored by people who have no experience in this field, don’t understand how these techniques are applied or function and/or are more interested in a sensational story than in the truth. The word click-bait springs to mind although certainly doesn’t apply equally to all.

Some testers are adamantly pro-usage of their DNA in order to identify victims and apprehend violent criminals. Other testers, not so much and some, on the other end of the spectrum are vehemently opposed. This is a highly personal topic with extremely strong emotions on both sides.

The first such case was the Golden State Killer, which has been followed in the past 18 months or so by another 100+ solved cases.

Regardless of whether or not people want their own DNA to be utilized to identify these criminals and victims, providing closure for families, I suspect the one thing we can all agree on is that we are grateful that these violent criminals no longer live among us and are no longer preying on innocent victims.

I wrote about the Golden State Killer, here, as well as other articles here, here, here and here.

In the genealogy community, various vendors have adopted quite different strategies relating to these kinds of searches, as follows:

  • Ancestry, 23andMe and MyHeritage – have committed to fight all access attempts by law enforcement, including court ordered subpoenas.
  • MyHeritage, Family Tree DNA and GedMatch allow uploads, so forensic kits, meaning kits from deceased remains or rape kits could be uploaded to search for matches, the same as any other kit. Law Enforcement uploads violate the MyHeritage terms of service. Both Family Tree DNA and GEDmatch have special law enforcement procedures in place. All three companies have measures in place to attempt to detect unauthorized forensic uploads.
  • Family Tree DNA has provided a specific Law Enforcement protocol and guidelines for forensic uploads, here. All EU customers were opted out earlier in 2019, but all new or existing non-EU customers need to opt out if they do not want their DNA results available for matching to law enforcement kits.
  • GEDmatch was recently sold to Verogen, a DNA forensics company, with information, here. Currently GEDMatch customers are opted-out of matching for law enforcement kits, but can opt-in. Verogen, upon purchase of GEDmatch, required all users to read the terms and conditions and either accept the terms or delete their kits. Users can also delete their kits or turn off/on law enforcement matching at any time.

New Concerns

Concerns in late 2019 have focused on the potential misuse of genetic matching to potentially target subsets of individuals by despotic regimes such as has been done by China to the Uighurs.

You can read about potential risks here, here and here, along with a recent DoD memo here.

Some issues spelled out in the papers can be resolved by vendors agreeing to cryptographically sign their files when customers download. Of course, this would require that everyone, meaning all vendors, play nice in the sandbox. So far, that hasn’t happened although I would expect that the vendors accepting uploads would welcome cryptographic signatures. That pretty much leaves Ancestry and 23andMe. I hope they will step up to the plate for the good of the industry as a whole.

Relative to the concerns voiced in the papers and by the DoD, I do not wish to understate any risks. There ARE certainly risks of family members being identified via DNA testing, which is, after all, the initial purpose even though the current (and future) uses were not foreseen initially.

In most cases, the cow has already left that barn. Even if someone new chooses not to test, the critical threshold is now past to prevent identification of individuals, at least within the US and/or European diaspora communities.

I do have concerns:

  • Websites where the owners are not known in the genealogical community could be collecting uploads for clandestine purposes. “Free” sites are extremely attractive to novices who tend to forget that if you’re not paying for the product, you ARE the product. Please be very cognizant and leery. Actually, just say no unless you’re positive.
  • Fearmongering and click-bait articles in general will prevent and are already causing knee-jerk reactions, causing potential testers to reject DNA testing outright, without doing any research or reading terms and conditions.
  • That Ancestry and 23andMe, the two major vendors who don’t accept uploads will refuse to add crypto-signatures to protect their customers who download files.

Every person needs to carefully make their own decisions about DNA testing and participating in sharing through third party sites.

Health

Not surprisingly, the DNA testing market space has cooled a bit this past year. This slowdown is likely due to a number of factors such as negative press and the fact that perhaps the genealogical market is becoming somewhat saturated. Although, I suspect that when vendors announce major new tools, their DNA kit sales spike accordingly.

Look at it this way, do you know any serious genealogists who haven’t DNA tested? Most are in all of the major databases, meaning Ancestry, 23andMe, FamilyTreeDNA, MyHeritage and GedMatch.

All of the testing companies mentioned above (except GEDmatch who is not a testing company) now have a Health offering, designed to offer existing and new customers additional value for their DNA testing dollar.

23andMe separated their genealogy and health offering years ago. Ancestry and MyHeritage now offer a Health upgrade. For existing customers, FamilyTreeDNA offers the Cadillac of health tests through Tovana.

I would guess it goes without saying here that if you really don’t want to know about potential health issues, don’t purchase these tests. The flip side is, of course, that most of the time, a genetic predisposition is nothing more and not a death sentence.

From my own perspective, I found the health tests to be informative, actionable and in some cases, they have been lifesaving for friends.

Whoever knew genealogy might save your life.

Innovative Third-Party Tools

Tools, and fads, come and go.

In the genetic genealogy space, over the years, tools have burst on the scene to disappear a few months later. However, the last few years have been won by third party tools developed by well-known and respected community members who have created tools to assist other genealogists.

As we close this decade, these are my picks of the tools that I use almost daily, have proven to be the most useful genealogically and that I feel I just “couldn’t live without.”

And yes, before you ask, some of these have a bit of a learning curve, but if you are serious about genealogy, these are all well worthwhile:

  • GedMatch – offers a wife variety of tools including triangulation, half versus fully identical segments and the ability to see who your matches also match. One of the tools I utilize regularly is segment search to see who else matches me on a specific segment, attached to an ancestor I’m researching. GedMatch, started by genealogists, has lasted more than a decade prior to the sale in December 2019.
  • Genetic Affairs – a barn-burning newcomer developed by Evert-Jan Blom in 2018 wins this years’ “Best” award from me. Genetic Affairs offers clustering, tree building between your matches even when YOU don’t have a tree. You can read more here.

2019 genetic affairs.png

Just today, Genetic Affairs released a new cluster interface with DNAPainter, example shown above.

  • DNAPainter – THE chromosome painter created by Jonny Perl just gets better and better, having added pedigree tree construction this year and other abilities. I wrote a composite instructional article, here.
  • DNAGedcom.com and Genetic.Families, affiliated with DNAAdoption.org – Rob Warthen in collaboration with others provides tools like clustering combined with triangulation. My favorite feature is the gathering of all direct ancestors of my matches’ trees at the various vendors where I’ve DNA tested which allows me to search for common surnames and locations, providing invaluable hints not otherwise available.

Promising Newcomer

  • MitoYDNA – a non-profit newcomer by folks affiliated with DNAAdoption and DNAGedcom is designed to replace YSearch and MitoSearch, both felled by the GDPR ax in 2018. This website allows people to upload their Y and mitochondrial DNA results and compare the values to each other, not just for matching, which you can do at Family Tree DNA, but also to see the values that do and don’t match and how they differ. I’ll be taking MitoYDNA for a test drive after the first of the year and will share the results with you.

The Future

What does the future hold? I almost hesitate to guess.

  • Artificial Intelligence Pedigree Chart – I think that in the not-too-distant future we’ll see the ability to provide testers with a “one and done” pedigree chart. In other words, you will test and receive at least some portion of your genealogy all tidily presented, red ribbon untied and scroll rolled out in front of you like you’re the guest on one of those genealogy TV shows.

Except it’s not a show and is a result of DNA testing, segment triangulation, trees and other tools which narrow your ancestors to only a few select possibilities.

Notice I said, “the ability to.” Just because we have the ability doesn’t mean a vendor will implement this functionality. In fact, just think about the massive businesses built upon the fact that we, as genealogists, have to SEARCH incessantly for these elusive answers. Would it be in the best interest of these companies to just GIVE you those answers when you test?

If not, then these types of answers will rest with third parties. However, there’s a hitch. Vendors generally don’t welcome third parties offering advanced tools and therefore block those tools, even though they are being used BY the customer or with their explicit authorization to massage their own data.

On the other hand, as a genealogist, I would welcome this feature with open arms – because as far as I’m concerned, the identification of that ancestor is just the first step. I get to know them by fleshing out their bones by utilizing those research records.

In fact, I’m willing to pony up to the table and I promise, oh-so-faithfully, to maintain my subscription lifelong if one of those vendors will just test me. Please, please, oh pretty-please put me to the test!

I guess you know what my New Year’s Wish is for this and upcoming years now too😊

What About You?

What do you think the high points of 2019 have been?

How about the decade?

What do you think the future holds?

Do you care to make any predictions?

Are you planning to focus on any particular goal or genealogy problem in 2020?

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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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Triangulation in Action at MyHeritage

Recently, I published the article, Hitting a Genealogy Home Run Using Your Double-Sided Two-Faced Chromosomes While Avoiding Imposters. The “Home Run” article explains why you want to use a chromosome browser, what you’re seeing and what it means to you.

This article, and the rest in the “Triangulation in Action” series introduces triangulation at FamilyTreeDNA, MyHeritage, 23andMe, GedMatch and DNAPainter, explaining how to use triangulation to confirm descent from a common ancestor. You may want to read the introductory article first.

This first section, “What is Triangulation” is a generic tutorial. If you don’t need the tutorial, skip to the “Triangulation at MyHeritage” section.

What is Triangulation?

Think of triangulation as a three-legged stool – a triangle. Triangulation requires three things:

  1. At least three (not closely related) people must match
  2. On the same reasonably sized segment of DNA and
  3. Descend from a common ancestor

Triangulation is the foundation of confirming descent from a common ancestor, and thereby assigning a specific segment to that ancestor. Without triangulation, you might just have a match to someone else by chance. You can confirm mathematical triangulation, numbers 1 and 2, above, without knowing the identity of the common ancestor.

Reasonably sized segments are generally considered to be 7cM or above on chromosomes 1-22 and 15cM or above for the X chromosome.

Boundaries

Triangulation means that all three, or more, people much match on a common segment. However, what you’re likely to see is that some people don’t match on the entire segment, meaning more or less than others as demonstrated in the following examples.

FTDNA Triangulation boundaries

You can see that I match 5 different cousins who I know descend from my father’s side on chromosome 15 above. “I” am the grey background against which everyone else is being compared.

I triangulate with these matches in different ways, forming multiple triangulation groups that I’ve discussed individually, below.

Triangulation Group 1

FTDNA triangulation 1

Group 1 – On the left group of matches, above, I triangulate with the blue, red and orange person on the amount of DNA that is common between all of them, shown in the black box. This is triangulation group 1.

Triangulation Group 2

FTDNA triangulation 2

Group 2 – However, if you look just at the blue and orange triangulated matches bracketed in green, I triangulate on slightly more. This group excludes the red person because their beginning point is not the same, or even close. This is triangulation group 2.

Triangulation Group 3 and 4

FTDNA triang 3

Group 3 – In the right group of matches, there are two large triangulation groups. Triangulation group 3 includes the common portions of blue, red, teal and orange matches.

Group 4 – Triangulation group 4 is the skinny group at right and includes the common portion of the blue, teal and dark blue matches.

Triangulation Groups 5 and 6

FTDNA triang 5

Group 5 – There are also two more triangulation groups. The larger green bracketed group includes only the blue and teal people because their end locations are to the right of the end locations of the red and orange matches. This is triangulation group 5.

Group 6 – The smaller green bracketed group includes only the blue and teal person because their start locations are before the dark blue person. This is triangulation group 6.

There’s actually one more triangulation group. Can you see it?

Triangulation Group 7

FTDNA triang 7

Group 7 – The tan group includes the red, teal and orange matches but only the areas where they all overlap. This excludes the top blue match because their start location is different. Triangulation group 7 only extends to the end of the red and orange matches, because those are the same locations, while the teal match extends further to the right. That extension is excluded, of course.

Slight Variations

Matches with only slight start and end differences are probably descended from the same ancestor, but we can’t say that for sure (at this point) so we only include actual mathematically matching segments in a triangulation group.

You can see that triangulation groups often overlap because group members share more or less DNA with each other. Normally we don’t bother to number the groups – we just look at the alignment. I numbered them for illustration purposes.

Shared or In-Common-With Matching

Triangulation is not the same thing as a 3-way shared “in-common-with” match. You may share DNA with those two people, but on entirely different segments from entirely different ancestors. If those other two people match each other, it can be on a segment where you don’t match either of them, and thanks to an ancestor that they share who isn’t in your line at all. Shared matches are a great hint, especially in addition to other information, but shared matches don’t necessarily mean triangulation although it’s a great place to start looking.

I have shared matches where I match one person on my maternal side, one on my paternal side, and they match each other through a completely different ancestor on an entirely different segment. However, we don’t triangulate because we don’t all match each other on the SAME segment of DNA. Yes, it can be confusing.

Just remember, each of your segments, and matches, has its own individual history.

Imputation Can Affect Matching

Over the years the chips on which our DNA is processed at the vendors have changed. Each new generation of chips tests a different number of markers, and sometimes different markers – with the overlaps between the entire suite of chips being less than optimal.

I can verify that most vendors use imputation to level the playing field, and even though two vendors have never verified that fact, I’m relatively certain that they all do. That’s the only way they could match to their own prior “only somewhat compatible” chip versions.

The net-net of this is that you may see some differences in matching segments at different vendors, even when you’re comparing the same people. Imputation generally “fills in the blanks,” but doesn’t create large swatches of non-existent DNA. I wrote about the concept of imputation here.

What I’d like for you to take away from this discussion is to be focused on the big picture – if and how people triangulate which is the function important to genealogy. Not if the start and end segments are exactly the same.

Triangulation Solutions

Each of the major vendors, except Ancestry who does not have a chromosome browser, offers some type of triangulation solution, so let’s look at what each vendor offers. If your Ancestry matches have uploaded to GedMatch, Family Tree DNA or MyHeritage, you can triangulate with them there. Otherwise, you can’t triangulate Ancestry results, so encourage your Ancestry matches to transfer.

I wrote more specifically about triangulation here and here.

Let’s start by looking at triangulation at MyHeritage.

Triangulation at MyHeritage

MyHeritage offers triangulation integrated into their chromosome browser.

Triangulation MyHeritage matches.png

At MyHeritage, select DNA Matches from the DNA dropdown menu, then click on the purple “Review DNA Match” of the person you want to compare. We re looking at my cousin, Cheryl F.

Triangulation MyHeritage review.png

When reviewing my DNA match with Cheryl, I can see the list of people that Cheryl and I both match, including my mother, first on the list. In addition to my mother’s relationship to me, I can also see an estimate of how closely my mother matches the other person – in this case, Cheryl. Cheryl is my mother’s first cousin (1C) and my first cousin, once removed (1C1R.)

Triangulation MyHeritage icon

Click to enlarge

For triangulation, the important image is the little purple icon at right, above.

Clicking on the purple triangulation icon shows the segments where Cheryl, my mother and I all three match and triangulate.

Finding my mother among Cheryl’s close matches tells me immediately which parent I share with Cheryl.

The areas on the chromosome browser below in the rounded squares are triangulated, meaning that I match Cheryl and the other person (who just happens to be my mother) on that same segment.

Triangulation MyHeritage browser.png

Showing triangulation with Cheryl and my mother provides a great example, because of course I triangulate with Cheryl and my mother on every segment where I match Cheryl – because I inherited all of those segments through my mother.

However, as far as triangulation goes, the fact that two of those people are closely related, me and my mother, makes it the same as only two people matching – Mom and Cheryl. Still, since Mom and Cheryl are first cousins, that match confirms my great-grandparents.

Cheryl carries pieces of my great-grandparent’s DNA that my mother doesn’t though, so matches in common with Cheryl may prove very genealogically useful.

At the top right of this chromosome browser page, I can “add or remove DNA matches” from my match list. I can look through my match list to find another close relative to see if they triangulate or I can download my match list to see who else matches me on that same segment. Instructions for the file download are at the end of this section.

Same Segment Matches

To illustrate that people will match you on the same segment, but don’t match each other because they descend from different sides of your family, I’ll add some cousins from my father’s side of the family.

I’m going to select cousins Charlene and David, and remove my mother.

Below, we show chromosome 3 again, but the triangulation bracket is gone. This tells us that this segment does NOT triangulate between me and ALL three people.

Please note that I may triangulate with some of the people. The absence of the bracket only means that I don’t triangulate with ALL of them.

I already know that while I match Cheryl, Charlene and David on this segment, only David and Charlene match each other because they are both from my father’s side, and Cheryl doesn’t match either of them because she is on my mother’s side.

Triangulation MyHeritage segments

Click to enlarge

To prove this, and to determine triangulation groups, I can compare the people two by two and continue adding people to see if they continue to triangulate.

Below, I’ve removed Cheryl, and I triangulate on chromosome 3 with both Charlene and David. The triangulation bracket appears.

Triangulation MyHeritage chromosome 3

Click to enlarge

Therefore, I know that Charlene and David descend through one of my parents, and Cheryl through the other – even if I didn’t know anything else at this point.

To reiterate, triangulation at MyHeritage means triangulation with everyone showing at the same time on the chromosome browser.

Other Resources to Identify Common Ancestors

For additional information, I can check the match information with each person to see if our trees, surnames or locations intersect.

SmartMatches and Theories of Family Relativity each provide clues and help to explain why we might triangulate.

SmartMatches tell you that you and another person share an ancestor in your and their tree, BUT, that common person may not be a direct ancestor of one or both of you. You also may or may not be DNA matches, and if so, your DNA match may or may not be through that ancestor.

Theories of Family Relativity (TOFR,) on the other hand, tell you that not only do you have a DNA match with this person, but that you have a common ancestor, and who that ancestor is. Sometimes the connection is made for you, even if one or both of you don’t show that ancestor in your tree simply because you have not extended your tree back far enough in time.

I wrote about how to use Theories of Family Relativity here.

Downloading Matches

You can request to download your matches list and also your shared DNA segments at MyHeritage by clicking on the three dots to the right at the top of your match list, then click on the option you wish. The resulting files will be e-mailed to you a few minutes later. If they don’t arrive, be sure to check your spam filter.

Triangulation MyHeritage export.png

Downloading your match list and/or shared DNA segments is NOT the same thing as downloading your raw data file to upload elsewhere. You’ll find those instructions in the Transfer section later in this article.

What About You?

Do you have a tree at MyHeritage?

Triangulation MyHeritage tree tab.png

If not, click on Family Tree to create or upload one including not only direct line ancestors, but their children and grandchildren which facilitates and encourages the formation of Theories of Family Relativity.

Connecting Your DNA to Your Tree

Assigning your kit and those of family members to the proper profile card in your tree is very important, especially for the formation of Theories of Family Relativity

To suggest a theory, MyHeritage searches through all the possible links in the MyHeritage database meaning SmartMatches between trees, Record matches, record to record matches, etc.

If a DNA kit is not associated with an individual that is connected to ancestors, this reduces the probability that MyHeritage will be able to find a theory.

For example, if I took a DNA test but only have myself in the tree, not connected to my father and mother, but my father appears in another user’s tree (and there are more ancestors in that tree) MyHeritage won’t be able to find the information to generate a theory.

If I add my father, then the system has a common ancestor to work with.

When the TOFR algorithm runs, it’s trying to find any possible route to connect the two individuals (you and your DNA Match). If you are associated with individuals in multiple sites or trees, MyHeritage will try all of them and generate multiple paths for you to evaluate.

Have you assigned the kits of family members you manage to the proper place in your tree?

Triangulation MyHeritage tree.png

You can do this easily under the Manage DNA Kits option, under the DNA tab. Click on the three little dots to the right of the kit.

Triangulation MyHeritage assign dots.png

Then click assign the kit.

Triangulation MyHeritage assign kit.png

You’ll be prompted

Triangulation MyHeritage kit name.png

If you start typing, you’ll be prompted with the names of people in your tree.

Other Resources to Identify Common Ancestors

MyHeritage includes other tools to help you identify common ancestors as well, including:

  • SmartMatches where MyHeritage matches individuals in trees
  • AutoClusters showing groups of people that match you and each other
  • Shared Matches indicating common DNA matches between you and another DNA match
  • Shared Ancestral Surnames show common surnames, even if a common ancestor does not show in a tree
  • Shared Ancestral Places indicating common locations in trees
  • Shared Ethnicities comparing ethnicity between matches, a feature typically only beneficial if looking for a minority (to you) ancestry match
  • Genealogical Records including matches from other databases such as Geni.com and FamilySearch
  • Trees

Transfers

Have you tested family members, especially everyone in the older generations? You can transfer their kits from Ancestry, 23andMe or FamilyTreeDNA if they’ve already tested there to MyHeritage.

The article, Are You DNA Testing the Right People? explains how to determine who to test. Make sure you aren’t missing anyone that you need.

Here’s how to transfer:

I wrote recently about how to work with triangulation at FamilyTreeDNA. Join me soon for similar articles about how to work with triangulation at 23andMe, GedMatch and DNAPainter.

Most of all – 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 Services

Genealogy Research

Genetic Affairs Reconstructs Trees from Genetic Clusters – Even Without Your Tree or Common Ancestors

Since Genetic Affairs launched in 2018, they’ve added a LOT of new functionality. I initially wrote about their clustering functionality here.

Genetic Affairs AutoClustering, SuperClusters and brand-new AutoTree tree reconstruction are to-die-for features for traditional genealogists. For adoptees or people seeking unknown parentage, they are the best thing since sliced bread, automating tasks previously peformed manually over labor-filled hours, days and months.

Why Genetic Affairs?

Genetic Affairs works with matches from three vendors; Ancestry, FamilyTreeDNA’s Family Finder test and 23andMe.

MyHeritage has integrated a version of Genetic Affairs directly into their product offering on the MyHeritage website so every MyHeritage DNA customer receives clustering functionality, free, through MyHeritage, but not tree reconstruction.

GedMatch has also implemented an autocluster version for Tier 1 users, but GedMatch’s version only works at GedMatch, of course, and does not include the new tree reconstruction feature.

This article pertains to the functionality of the features available directly through Genetic Affairs, including:

  • Clustering your matches visually to identify ancestral lines of people that match you and each other
  • Reports by cluster including common surnames and locations
  • Analysis of trees within each cluster to identify common ancestors
  • Partially reconstructs trees with your known ancestors for each cluster
  • Partially reconstructs trees between your matches even if you don’t have a tree or don’t share the common ancestor

Genetic Affairs provides visualization for linked DNA matches along with critically important clues to help you figure out just how you are related to these people, and these clusters of interrelated people. The Genetic Affairs user manual can be found here.

Analysis

Each time you run Genetic Affairs is called an analysis. Each analysis scans your kit at the selected vendor(s) for all current matches. A few minutes later, you receive a zip file via e-mail with two or three files depending on your selections at Genetic Affairs and the tree availabilty of the vendor:

  • Autocluster file including the visual clusters plus additional information
  • Excel spreadsheet of cluster members and relevant information such as common ancestors and common locations
  • Tree file containing reconstructed trees (23andMe does not support trees, so no trees are available for 23andMe clusters)

Let’s look at each feature. Grab a cup of coffee and head for the computer.

Selecting Analysis Options

I encourage you to experiment. Selecting a wider range of cM (centimorgans) results in a larger file, but may also mean that the analysis times out.

For this report, I’m utilizing my matches at FamilyTreeDNA and selected a cM range of 50 minimum and 250 maximum. I wanted a minimum cluster size of 2 people, meaning 2 in addition to me. This resulted in 249 total matches that met that criteria and 20 people who met the cM criteria but did not have another person with whom to cluster.

I tried a second analysis using 20 cM – 300 cM resulting in a much larger file with 499 people in the cluster group. Currently, 499 is the maximum that will be processed.

Genetic Affairs profiles.png

On the Genetic Affairs Profiles page, I can view all of the profiles I manage. Users can schedule updates where Genetic Affairs automatically scans for matches and produces reports.

Genetic Affairs my profiles

Click to enlarge

By clicking on the Autoscan button, you can schedule automated recurring scans with e-mail notification.

Genetic Affairs autoscan

Click to enlarge

You can scan daily, weekly, monthly or never – whatever interval you select.

You can select both the minimum level of DNA match and the minimum cM. The lowest you can select is 9cM.

You can view any e-mails that have been sent to you by Genetic Affairs. The green envelope means that there’s something in your e-mail box. This answers the question about whether the report was completed and sent. If the report has been sent, but is not in your e-mail, check your spam filter.

Starting the Scan

Back on the Genetic Affairs profiles page, you can initiate an autocluster by clicking on the AutoCluster button where you’ll see the options based on which vendor you’ve selected.

Genetic Affairs autocluster.png

For example, at Ancestry, you can include only people in a particular group or only starred matches.

Genetic Affairs Ancestry autocluster

Click to enlarge

23andMe includes surname enrichment and triangulated groups options.

Genetic Affairs 23andme autocluster.png

FamilyTreeDNA and Ancestry both include the “AutoTree – identify common ancestors from trees” option. It’s very important that you click this box if you select the “Default AutoCluster” option – or you won’t get the reconstructed trees.

Genetic Affairs default autocluster.png

Of course, you can always run the analysis again.

Genetic Affairs autotree.png

If you click on the “AutoTree AutoCluster” function, the AutoTree box is already checked for you.

Genetic Affairs autotree autocluster.png

Rule Based AutoCluster

The “Rule based AutoCluster” is a dream-come-true for people seeking unknown parents or ancestors in a relatively recent timeframe.

Genetic Affairs Rule Based Autocluster.png

The “Rule based AutoCluster” provides you with options that allow you to do three things:

  • NOT – Exclude your matches with someone else. For example, your mother has tested. You can use the NOT rule to exclude anyone you might match through your mother’s side, providing you with clusters from your father’s side.
  • AND – Combine your results with someone else’s. If you have identified a half-sibling, you can view only clusters of only people who match you AND your half sibling.
  • OR – Combined rules. You can request a cluster of everyone in clusters with person A but not in a cluster with person B. In this case, if you match a number of half siblings, you can include all of their matches, except people who match them through their “other” parent, if that parent has tested.

Genetic Affairs has provided some graphics and examples here, but you may have to be a member of the site to access this page because the options are customized for you. So I’ll include the non-customized information, below. You can click these to open in a separate window and enlarge.

Genetic Affairs rule based 1.pngGenetic Affairs rule based 2.png

The “Rule based AutoCluster” explanations provided by Genetic Affairs.

Genetic Affairs rule based 3.png

Read the details of how these tools work. They are powerful, so don’t assume you understand without reading carefully.

Now let’s cluster!

Clustering Your Matches

Genetic Affairs autocluster order.png

At Genetic Affairs, if you initiate clustering by clicking on the AutoCluster button, you’ll need to put a checkmark in the AutoTree function box. If you began by clicking the AutoTree button, the box is automatically checked for you.

A few minutes later, you’ll receive an email with a zipped file. Save this file to someplace on your computer where you can find it, and open the zipped file by clicking.

Genetic Affairs zip file.png

You’ll see the files, above.

Click on the chrome AutoCluster HTML file which will display in your browser.

The first thing you will see is your visual autocluster. It’s so much fun to watch your matches “fly” into place!

Each of the people in this cluster are somehow related to the other people in the custer who have cells of the same color. The people with grey cells are included in two clusters – meaning the one to the right and the one above, both.

Genetic Affairs cluster.png

The names of the matches are listed to the left and above the display.

The legend is to the right.

Genetic Affairs cluster legend.png

I have a total of 41 clusters.

Scrolling down the page, each cluster has additional information, and each column is searchable or selectable, including comments I’ve entered at the vendor.

Genetic Affairs autocluster info

Click to enlarge

Just by looking at these first 3 matches, I know immediately which side of the family and which ancestors are involved with this cluster. I can look at my notes, to the right, which indicate whether I’ve identified our common ancestor. I paint identified matches at DNAPainter which I’ve entered into the notes field at the vendor.

If I’m signed in to my account at the vendor, I can click on my match’s tree link, above, and take a look. Keep in mind that these people can be related to you, and each other, through multiple ancestors.

Genetic Affairs autocluster members.png

You can hover over any person in the grid, above, to view additional information. For each person whose square is grey, indicating membership in (at least) two clusters, you can hover over the grey square and view the members of both clusters. In this case, I’m hovered over the grey square of Brooke and E.H and the black box shows me who is in both people’s clusters.

Note that while a match could be related to you through several ancestors, and hence be in more than 2 clusters, because of the grid nature of clustering, a match can only be displayed in a maximum of 2 different clusters.

Looking at the auto-generated table below, I see the common surnames in cluster 1. Keep in mind that many of these people maybe related to each other through a spouse that you aren’t. Your ancestor’s brother’s children, for example, are also related to each other through your ancestor’s brother’s wife.

Genetic Affairs surnames.png

I know that Vannoy is the common line, but Upton isn’t my ancestor – at least not that I know of. However, a surname with 20 people in a cluster needs to be investigated and evaluated. Do I have any missing wives in this line? Here’s a really great place to start digging.

In this case, it turns out that one of my ancestor’s children married an Upton, and several of his descendants have tested.

Let’s see what other tools we have.

The Ancestor Spreadsheet

Opening the spreadsheet file, I see several rows and columns.

Genetic Affairs common ancestor

Click to enlarge

The common ancestor between the people in the rows is listed at left. The green cells are from my tree.

Two example ancestors are shown above, Mary McDowell and William Harrell, who just happen to have been married to each other.

Scrolling on down, I see rows without green cells.

Genetic Affairs ancestors

Click to enlarge

These people share a common ancestor in their trees, an ancestor that isn’t in my tree. Presumably this is an ancestor I don’t share with them – or one I haven’t identified.

For example, “Bev” and “van” share William Grubb. “Vicki” and “Mark” share Martha Helen Smith. I don’t share either of these ancestors, but Martha Smith married Alvis Winster Bolton, the son of my ancestor – so I know why Martha Helen Smith appears as a common person in the trees of my matches, but not me.

Further down in the same cluster, I notice that one match shares multiple lines in our trees. Therefore, our DNA match could be on either line, or some segments from one line and some from the other.

Scrolling to the bottom of each cluster’s sheet, common locations are provided.

Genetic Affairs locations

Click to enlarge

While the designation of “Tennessee” isn’t terribly exciting, scrolling further down provides a list by county, and that IS exciting, especially if you’re chasing a brick wall. Sometimes a group of ancestors in a location where you’re seeking a female’s family is very suggestive especially when combined with ancestral names and surnames.

Let’s move on to the third group of files, Trees.

The Tree File

Click on the tree file and you’ll see the following.

Genetic Affairs tree file.png

Reconstructed Trees

For each cluster where trees can be reconstructed, you’ll see two files for cluster 1:

  • Ancestors 1
  • Tree 1

Opening the file labeled Ancestors 1, I see the following information for the first ancestor, meaning a common ancestor between the two people listed below that ancestor. You can click to enlarge these images.

Genetic Affairs ancestors by cluster.png

Opening the corresponding Tree 1 file, I see that Genetic Affairs has reconstructed the tree between me and the other testers as best it can based on the provided trees.

Genetic Affairs reconstructed trees.png

Looking at the tree for cluster 3, below, I see this line in cluster 1, above, has been extended because Sarah, the pink match and me all share a common ancestor, Elizabeth Shepherd.

Genetic Affairs reconstructed tree 2.png

Looking at another cluster, below, while I don’t share an ancestor in a tree, three people that I match at a relatively high level do.

Genetic Affairs reconstructed tree no common ancestor.png

As you can see, their common ancestor is Anne Adelaide Chiasson. This is my Acadian line, so our common ancestor or ancestors must be someplace on up that tree, or the result of an undocumented adoption, or a missing ancestor in our trees.

Constructing the trees of your matches to each other, even when you don’t have a common ancestor in your tree, is the best feature of all.

Clustering plus tree reconstruction, especially in combination with the other clues, is the key to breaking through those unyielding  brick walls.

Super AutoClusters

Just as I was getting ready to publish this article, Genetic Affairs released a new feature called Super AutoCluster.

I absolutely love this, because it combines your clusters from multiple vendors – today Ancestry, who does not provide segment information, along with Family Tree DNA, who  provides invaluable segment information.

This combination can be extremely powerful.

To begin a Super AutoCluster, click on that option under an AncestryDNA kit that also has a kit at Family Tree DNA. Both kits need to have a profile at Genetic Affairs.

Genetic Affairs supercluster.png

Next, you’ll see the screen confirming the kits to use. The combined autocluster tool is limited to a total of 500 matches, or 250 at each account. However, that’s more than enough to make some great progress.

Press “Perform Analysis.”

Drum roll please…

Voila, your combined cluster.

Genetic Affairs supercluster cluster

Click to enlarge

In this example, you can see the large peach and purple Ancestry clusters. The green red, brown and pink smaller clusters are Family Tree DNA clusters. The Family Tree DNA clusters have tiny little Fs in their cells. If you click the above graphic to enlarge, you can see the Fs.

However, the grey cells that intersect the two clusters, meaning an Ancestry and a Family Tree DNA cluster, are found in both of those clusters, connecting the clusters for you logically.

If you look closely at the cells labeled here with “common names,” you’ll see “N” in the cells indicating a common names for you to check out within that cluster.

The “Common Ancestors” box shows the people who connect to both clusters.

There are also a number of people that span the green and red Family Tree DNA clusters too.

Genetic Affairs then proceeds to combine the clustered DNA matches and trees for you from both vendors.

Genetic Affairs supercluster tree

Click to enlarge

In addition to the cluster graph and spreadsheet information that now includes combined information, you’ll see a much larger clustered tree.

And again, the best part is that even if you don’t know how you connect to people through trees, their tree and ancestors will be connected, even if you’re absent. You’ll be present in the genetic cluster itself, so you can work the combined tree cluster to see where you might fit in that branch of the family. Because trust me, you do fit – somehow, someplace.

Cost

Genetic Affairs uses a “credit” payment system. Your first 200 credits are free so you can learn. These may last you for weeks or months, depending on how often you run the clusters. If you manage multiple kits, you’ll use credits more quickly, but it’s worth every last dollar. Genetic Affairs is very inexpensive. I manage multiple accounts and I spend around $5 per month. You can read about Genetic Affairs’ payment plans and see sample calculations here.

My recommendation is simply to dive in and use your free credits. By the way, I’m gifting myself with a “credit purchase” for Christmas😊

Genetic Affairs is a wonderful genealogy gift idea for serious genealogists, adoptees or people seeking unknown parents or ancestors in recent generations.

Have You Tested or Transferred With All 4 Vendors?

If you haven’t yet tested at or transferred to each of the main 4 vendors, clustering, reconstructed trees and SuperClusters is yet another reason to do so. Additionally, every close relative’s DNA holds hints that yours doesn’t, so be sure to test them too.

You can purchase kits, below, or read about how to transfer your DNA to vendors who accept uploads – FamilyTreeDNA, MyHeritage and GedMatch, all for free, here.

Enjoy!

______________________________________________________________

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

Triangulation in Action at Family Tree DNA

Recently, I published the article, Hitting a Genealogy Home Run Using Your Double-Sided Two-Faced Chromosomes While Avoiding Imposters. The “Home Run” article explains why you want to use a chromosome browser, what you’re seeing and what it means to you.

This article, and the rest in the “Triangulation in Action” series introduces triangulation at Family Tree DNA, MyHeritage, 23andMe, GedMatch and DNAPainter, explaining how to use triangulation to confirm descent from a common ancestor. You may want to read the introductory article first.

What is Triangulation?

Think of triangulation as a three-legged stool – a triangle. Triangulation requires three things:

  1. At least three (not closely related) people must match
  2. On the same reasonably sized segment of DNA and
  3. Descend from a common ancestor

Triangulation is the foundation of confirming descent from a common ancestor, and thereby assigning a specific segment to that ancestor. Without triangulation, you might just have a match to someone else by chance. You can confirm mathematical triangulation, numbers 1 and 2, above, without knowing the identity of the common ancestor.

Boundaries

Triangulation means that all three, or more, people much match on a common segment. However, what you’re likely to see is that some people don’t match on the entire segment, meaning more or less than others as demonstrated in the following examples.

FTDNA Triangulation boundaries.png

You can see that I match 5 different cousins who I know descend from my father’s side on chromosome 15 above. As always, I’m the background grey and these matches are all being compared against me.

I triangulate with them in different ways, forming multiple triangulation groups that I’ve discussed individually, below.

Triangulation Group 1

FTDNA triangulation 1.png

Group 1 – On the left group of matches, above, I triangulate with the blue, red and orange person on the amount of DNA that is common between all of them, shown in the black box. This is triangulation group 1.

I’ve overlayed additional triangulation groups below, so you can compare the groups.

Triangulation Group 2

FTDNA triangulation 2.png

Group 2 – However, if you look just at the blue and orange triangulated matches bracketed in green, I triangulate on slightly more, extending to the left. This group excludes the red person because their beginning point is not the same, or even close. This is triangulation group 2.

Triangulation Group 3 and 4

FTDNA triang 3.png

Group 3 – At right, we see two large triangulation groups. Triangulation group 3 includes the common portions of blue, red, teal and orange matches.

Group 4 – Triangulation group 4 is the skinny group at far right and includes the common portion of the blue, teal and dark blue matches.

Triangulation Groups 5 and 6

FTDNA triang 5.png

Group 5 – There are also two more triangulation groups. The larger green bracketed group includes only the blue and teal people because their end locations are to the right of the end locations of the red and orange matches. The start location varies as well. This is triangulation group 5.

Group 6 – The smaller green bracketed group includes only the blue and teal person because their start locations are before the dark blue person. This is triangulation group 6.

There’s actually one more triangulation group. Can you spot it?

Triangulation Group 7

FTDNA triang 7.png

Group 7 – The tan group includes the red, teal and orange matches but only the areas where they all overlap. This excludes the top blue match because their start location is different. Triangulation group 7 only extends to the end of the red and orange matches, because those are the same locations, while the teal match extends further to the right. That extension is excluded in this group, of course.

Slight Variations

Matches with only slight start and end differences are probably descended from the same ancestor, but we can’t say that for sure (at this point) so we only include actual mathematically matching segments in a triangulation group.

You can see that triangulation groups often overlap because group members share more or less DNA with each other. Normally we don’t bother to number the groups – we just look at the alignment. I numbered them for illustration purposes.

Shared or In-Common-With Matching

Triangulation is not the same thing as a 3-way shared “in-common-with” match. You may share DNA with those two people, but on entirely different segments from entirely different ancestors. If those other two people match each other, it can be on a segment where you don’t match either of them, and thanks to an ancestor that they share who isn’t in your line at all. Shared matches are a great hint, especially in addition to other information such as Phased Family Matching which we’ll talk about in a minute, but shared matches don’t necessarily mean triangulation has occurred, although it’s a great place to start looking.

I have shared matches where I match one person on my maternal side, one on my paternal side, and they match each other through a completely different ancestor on an entirely different segment. However, we don’t triangulate because we don’t all match each other on the SAME segment of DNA. Yes, it can be confusing.

Just remember, each of your segments, and matches, has its own individual history.

Imputation Can Affect Matching

Over the years the chips on which our DNA is processed at the vendors have changed. Each new generation of chips tests a different number of markers, and sometimes different markers – with the overlaps between the entire suite of chips being less than optimal.

I can verify that most vendors use imputation to level the playing field, and even though two vendors have never verified that fact, I’m relatively certain that they all do. That’s the only way they could match to their own prior “only somewhat compatible” chip versions.

The net-net of this is that you may see some differences in matching segments at different vendors, even when you’re comparing the same people. Imputation generally “fills in the blanks,” but doesn’t create large swatches of non-existent DNA. I wrote about the concept of imputation here.

What I’d like for you to take away from this discussion is to be focused on the big picture – if and how people triangulate which is the function important to genealogy. Not if the start and end segments are exactly the same.

Triangulation Solutions

Each of the major vendors, except Ancestry who does not have a chromosome browser, offers some type of triangulation solution, so let’s look at what each vendor offers. If your Ancestry matches have uploaded to GedMatch, Family Tree DNA or MyHeritage, you can triangulate with them there. Otherwise, you can’t triangulate Ancestry results, so encourage your Ancestry matches to transfer.

You can find step-by-step transfer instructions to and from each vendor, here.

I wrote more specifically about triangulation here and here.

Let’s start by looking at triangulation at Family Tree DNA.

Triangulation at Family Tree DNA

Family Tree DNA has two different tools that can be used separately in different circumstances to determine whether or not your segments triangulate.

Phased Family Matching can be used for triangulation.

The Matrix tool can be utilized for people who aren’t designated through Phased Family Matching as maternal or paternal matches to suggest or eliminate triangulation.

First, go to the Family Finder section of your personal page.

We’ll be working with Matches, the Chromosome Browser, and the Matrix.

FTDNA triangulation page.png

Phased Family Matching

At Family Tree DNA, I’ve tested my cousins:

  • Cheryl, my mother’s first cousin (1C)
  • Charlene, my first cousin once removed (1C1R) on my father’s side
  • David, my second cousin (2C) on my father’s side.

I’ve linked the test results of those cousins to my tree in their proper location, which allows Family Tree DNA to do something called Phased Family Matching.

If you don’t have a tree and don’t link your DNA results and those of your family members, Family Tree DNA can’t perform Phased Family Matching.

I explained phasing in the introductory article.

Testing your parents is wonderful if that’s possible, but parents aren’t always available to test. At Family Tree DNA, you don’t need to have tested your parents in order to have phased matches.

In essence, Family Tree DNA uses the DNA of known cousins, third cousins or closer, to assign matches to maternal or paternal tabs, or sides, also sometimes referred to as buckets. I wrote about Phased Family Matching here and here.

FTDNA triang buckets.png

You can see that of my 4806 matches, 1101 are assigned to my paternal side, 884 to my maternal side and 4 are assigned to both.

FTDNA triang header.pngFTDNA triang Charlene.png

My cousin Charlene is assigned to my paternal side, as shown by the blue icon, because I linked her to the correct position in my tree, as is my cousin, David, below.

FTDNA triang David.png

Conversely, my cousin Cheryl is assigned maternally because I linked her as well.

FTDNA triang Cheryl.png

These specific people are assigned maternally and paternally because I linked them to their proper place in my tree. These matches will allows Family Tree DNA to link other testers to the proper side of my tree too, because they match me and my cousin on the same segments – in essence phasing a large number of my matches for me which facilitates triangulation.

Linking Matches on Your Tree

In order to cause Phased Family Matching, aka, “bucketing” to occur, I linked my own test and that of my known 3rd cousins or closer to their proper places in my tree at Family Tree DNA.

If you don’t create a tree or upload a GEDCOM file and link yourself and your known matches, your matches can’t be assigned to maternal and paternal sides.

FTDNA triang tree.png

By utilizing the matching DNA between you and known close relatives on your maternal and paternal sides, Family Tree DNA assigns other people who match both of you on those same segments to the same side of your tree.

If you select matches from the same side of your tree and they match on the same segments, they triangulate.

Of course, that’s assuming the person doesn’t match you on both sides of your tree.

You can also download your matching segments in a file and sort to see who matches on the same locations, but the parental side designation (bucketing) is not reflected in the segment download file. Bucketing is reflected in the match download file which is a different file.

There are two separate download files, but they can be merged.

Two Download Files

The first file, your match download file, provides information about your matches such as their haplogroups, surnames and contact information, including bucketing assignment, but not the actual matching segment data.

The match file tells you a great deal and is both sortable and searchable. You can search for any surname, for example, or you can sort for everyone in the Paternal or Maternal matching bucket. You can creatively combine parts of this file with the matching segments file in order to quickly flag the people on your paternal side. Knowledge about how to work with spreadsheets is a plus.

FTDNA triang match file

Click to enlarge

This download is available at the bottom of the Family Finder match page.

FTDNA triang match.png

You can download all of your matches, or just those in a filtered view, such as in-common-with or as the result of a surname search.

FTDNA triang download.png

The second file, your matching segments file, is available on the chromosome browser page.

The matching segments file includes the match name along with the matching chromosome segments and number of matching SNPs.

FTDNA triang segment file.png

If you click through to the chromosome browser from your main page, as shown below, with NO MATCHES SELECTED, you will be able to download ALL matching segments.

FTDNA triang browser.png

You’ll see “Download All Segments” in the upper right-hand corner.

FTDNA triang download all seg.png

From that Chromosome Browser page, you will also have the ability to select matches to show on the browser.

FTDNA triang browser select

If you select people on the match page before clicking on the chromosome browser or select matches on the chromosome browser page, then clicking on “Download Segments,” will only download the matching segments of the people that you have currently selected to match against in the browser.

FTDNA triang download seg.png

Combinations of Tools and Filters

  • The chromosome browser tells you if people match you on the same segment.
  • The in-common-with filter on the match page tells you who you match in common with a specific person, but not if those two people match each other.

Of course, if both people are assigned to your same parental side bucket, and they both only match you on one large segment – and it’s the same segment, then you must triangulate.

If they aren’t both assigned to a parental bucket, then you can’t make that determination using parental side designations.

Is there a tool that allows you to compare people against each other at the same time to see if your matches also match each other?

Glad you asked.

Yes, there is.

The Matrix

Let’s say that you want to see if a group of people who you match also match each other.

FTDNA triang matrix.png

Family Tree DNA provides a Matrix tool that allows you to select 10 (or fewer) matches in order to determine if your matches also match each other.

FTDNA triang matrix match.png

I’ve entered Cheryl, Charlene and David. You can see that David and Charlene match each other, and Cheryl doesn’t match either Charlene or David.

Of course, we know that’s accurate because:

  • I already know these people and their relationship to me and each other
  • These three people are already assigned to maternal and paternal sides or buckets, so the matrix is verifying what we already know
  • I know where they match on the same segment on the chromosome browser

FTDNA triang 3 browser.png

Even though they match on the same segment on the chromosome browser, the fact that they are bucketed to different parental sides, and that the matrix shows that Cheryl doesn’t match either Charlene and David, confirms that David and Charlene triangulate with me, while Cheryl is not a member of that triangulation group.

This is exactly why triangulation is important. Looking at the image above, the only thing you know is that they all 3 match you – but with the additional information about bucketing and the matrix, we know that only the two bottom people, Charlene and David triangulate with me. Note that I’ve added the maternal and paternal icons for clarity.

FTDNA triang match group browser.png

However, if I didn’t have this knowledge, or not everyone was bucketed, the Matrix tool would be extremely useful. The matrix tool uses the matching threshold of approximately 7.69 cM.

The matrix doesn’t tell you if these people match each other on the same segment where they match you,

However, there’s a good probability that they do, especially if only one matching segment is involved.

You can check the chromosome browser to see if they both match you on the same segment. It’s possible if they don’t match you on the same segment that they match each other on different segments, and possibly through a different ancestor. You may need to reach out to them to ask if they match each other, and if they have known genealogy if they aren’t bucketed.

By utilizing the Matrix tool, you can isolate people to maternal and paternal sides of your tree.

Other Resources to Identify Common Ancestors

Be sure to check other clues at Family Tree DNA such as:

Shared surnames, shown on your matches page, with common surnames that you share bolded

FTDNA triang surnames.png

Trees, indicated by the blue pedigree icon on the match page.

FTDNA triang pedigree.png

Y and mitochondrial DNA haplogroups and matching. You can view your matches haplogroup and other information by clicking on their profile picture on your matches page.

FTDNA triang profile.png

Advanced Matching can be utilized to see if you match on combined tests, or in common projects.

FTDNA triang advanced match.png

This article discusses the 9 different autosomal tools available at Family Tree DNA.

What About You?

Do you have a tree at Family Tree DNA?

Have you connected your test and any family members to your tree?

Can you test a family member, third cousins or closer, or have them transfer a kit from another vendor?

Here’s how to transfer:

How many people do you have on your paternal and maternal tabs on your Family Finder matches page?

You can paint every single one of the people who are designated as maternal or paternal at DNAPainter to your grandparents on the respective maternal or paternal side. DNAPainter Instructions and Resources will explain how, and why.

Join me soon for similar articles about how to work with triangulation at MyHeritage, 23andMe, GedMatch and DNAPainter.

Most of all – 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 Services

Genealogy Research

Duplicate Copies of Parental Chromosomes – Uniparental Disomy

Recently, three articles were been published that discuss a phenomenon where unsuspecting individuals have two copies one parent’s chromosome, and no copy of the other parent’s chromosome. This is called Uniparental Disomy.

Since then, online I’ve seen this phenomenon being offered as a reason for all kinds of things – which just isn’t the case.

I’m sure in part it’s because people either haven’t actually read the articles, or they don’t understand what’s being said.

I’m going to explain this briefly and then tell you how you can find out if this situation actually DOES apply to you.

Uniparental Disomy in Brief

Here are a few summary bullet points about uniparental disomy:

  • Uniparental disomy is found on ONLY ONE CHROMOSOME in roughly 1 in 2000 people in the reference samples utilized at 23andMe.
  • This is not a new discovery, per se. It was known and previously believed to occur in 1 of 3,500 births, but that frequency has been updated to 1 in 2,000 in the paper.
  • Uniparental disomy was found in 1 of 50,000 people on TWO CHROMOSOMES.
  • This is NOT the reason you have more maternal or paternal matches, in general. Legitimate reasons for more matches on one parent’s line include the fact that one family or another historically has more or fewer descendants, more or fewer dead ends, recent immigrants, ancestors from regions where DNA testing is not popular and/or endogamous populations.
  • The people included in the research were trios where the tester and their parents have all 3 tested.
  • Many/most people with uniparental disomy have no known health issues.
  • The testers have in some cases been associated with some conditions, as described in the paper and supplemental information.
  • Of the people who carry this condition, more people carry a double maternal chromosome than a double paternal chromosome.
  • Uniparental disomy occurs more on chromosome 16 than any other chromosome, twice as often as the second highest, chromosome 7, with 40 and 20 occurrences each, respectively. Chromosome 18 had none. No, no one knows why.
  • It’s not necessary for the entire chromosome to be duplicated. In some cases, only part of the chromosome is improperly combined.

Articles

This Atlantic article provides an overview:

This academic paper in Cell is referenced in The Atlantic article and is where the meat of the information is found. Be sure to look at the supplemental files too.

Much of the data for the article was from 23andMe who discussed this study in their blog here.

What About You?

Do you have a chromosome that has experienced uniparental disomy? Probably not, but there’s a very easy way for you to find out.

If you have a duplicate chromosome, or portion of a chromosome from one parent, the genetic genealogy “indicator” that you’ll see is called ROH, or Run of Homozygosity. This condition occurs in situations where you have a duplicate chromosome, or where your parents are related to each other

  1. The first question to ask yourself is whether or not your parents are related to each other. If so, you will have some ROH segments.
  2. The second question is whether you have an entire duplicated chromosome when your parents aren’t related.

In order to answer both questions, we use the tool at GedMatch called “Are your parents related?”

Are Your Parents Related to Each Other?

You’ll need to establish an account at GedMatch and upload your DNA results from one of the testing vendors.

Here are instructions for how to download from the various vendors:

Using the “Are your parents related” Tool

To use this tool at GedMatch, after your uploaded kit is finished processing, click on “Are your parents related?” and enter the kit number of the person you want to evaluate. I’m assuming for this discussion that person is you.

Parents related.png

Normally, we use this tool to determine if someone’s parents are related to each other. We find this occurring in endogamous populations or where cousins married in the past few generations, as happened rather routinely in history.

In those situations, across all of a person’s chromosomes (not just one), we find relatively small segments of common DNA inherited by the person on both their maternal and paternal copies of each chromosome.

Parents are related.png

These matching areas are called ROH or “runs of homozygosity” meaning that the DNA is identical on both chromosomes for short segments, as shown above in the regions where the top bars are solid green and the bottom bar is solid blue.

The legend for reading the graphic is shown below.

Parents related legend.png

The chromosomes of a person whose parents are not related is shown below. Notice that there are no significant green bars on top, and no blue bars on the bottom.

Parents not related.png

Simple chance alone is responsible for tiny segments that are identical, like those tiny green slivers, but not larger segments over 7cM as shown in the first example and marked by blue on the bottom.

For someone that has a fully duplicated chromosome, meaning uniparental disomy, we see something different.

A Duplicate Chromosome

For someone that has a duplicate parental chromosome, all of their chromosomes look normal except that one entire chromosome, or a very large segment, is entirely identical.

Below is an example of a person whose chromosome 7 is duplicated. The rest of this person’s chromosomes looked like the image above with only tiny green slivers.

Parents uniparental disomy.png

If you have a duplicate chromosome, you’re rare, one in every 2,000 people in the populations studied.

If you have two identical chromosomes, you’re hen’s teeth rare – 1 in 50,000.

If you have uniparental disomy, you probably have no idea. You can also experience uniparental disomy when most of, but not all of a single chromosome is duplicated.

If you have duplicate parental chromosomes, you’ll match people on both sides of your family normally on all of your OTHER non-duplicate chromosomes. On your duplicate chromosome, you’ll only match people from the parent whose chromosome is duplicated.

In other words, this is NOT why you seem to be missing matches from one side of your family generally. You’ll need to look at other reasons to explain that.

If you have a duplicate chromosome, or large segment of a duplicate chromosome, leave a comment.

______________________________________________________________

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

 

 

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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Native American & Minority Ancestors Identified Using DNAPainter Plus Ethnicity Segments

Ethnicity is always a ticklish subject. On one hand we say to be leery of ethnicity estimates, but on the other hand, we all want to know who our ancestors were and where they came from. Many people hope to prove or disprove specific theories or stories about distant ancestors.

Reasons to be cautious about ethnicity estimates include:

  • Within continents, like Europe, it’s very difficult to discern ethnicity at the “country” level because of thousands of years of migration across regions where borders exist today. Ethnicity estimates within Europe can be significantly different than known and proven genealogy.
  • “Countries,” in Europe, political constructs, are the same size as many states in the US – and differentiation between those populations is almost impossible to accurately discern. Think of trying to figure out the difference between the populations of Indiana and Illinois, for example. Yet we want to be able to tell the difference between ancestors that came from France and Germany, for example.

Ethnicity states over Europe

  • All small amounts of ethnicity, even at the continental level, under 2-5%, can be noise and might be incorrect. That’s particularly true of trace amounts, 1% or less. However, that’s not always the case – which is why companies provide those small percentages. When hunting ancestors in the distant past, that small amount of ethnicity may be the only clue we have as to where they reside at detectable levels in our genome.

Noise in this case is defined as:

  • A statistical anomaly
  • A chance combination of your DNA from both parents that matches a reference population
  • Issues with the reference population itself, specifically admixture
  • Perhaps combinations of the above

You can read about the challenges with ethnicity here and here.

On the Other Hand

Having restated the appropriate caveats, on the other hand, we can utilize legitimate segments of our DNA to identify where our ancestors came from – at the continental level.

I’m actually specifically referring to Native American admixture which is the example I’ll be using, but this process applies equally as well to other minority or continental level admixture as well. Minority, in this sense means minority ethnicity to you.

Native American ethnicity shows distinctly differently from African and European. Sometimes some segments of DNA that we inherit from Native American ancestors are reported as Asian, specifically Siberian, Northern or Eastern Asian.

Remember that the Native American people arrived as a small group via Beringia, a now flooded land bridge that once connected Siberia with Alaska.

beringia map

By Erika Tamm et al – Tamm E, Kivisild T, Reidla M, Metspalu M, Smith DG, et al. (2007) Beringian Standstill and Spread of Native American Founders. PLoS ONE 2(9): e829. doi:10.1371/journal.pone.0000829. Also available from PubMed Central., CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=16975303

After that time, the Native American/First Nations peoples were isolated from Asia, for the most part, and entirely from Europe until European exploration resulted in the beginning of sustained European settlement, and admixture beginning in the late 1400s and 1500s in the Americas.

Family Inheritance

Testing multiple family members is extremely useful when working with your own personal minority heritage. This approach assumes that you’d like to identify your matches that share that genetic heritage because they share the same minority DNA that you do. Of course, that means you two share the same ancestor at some time in the past. Their genealogy, or your combined information, may hold the clue to identifying your ancestor.

In my family, my daughter has Native American segments that she inherited from me that I inherited from my mother.

Finding the same segment identified as Native American in several successive generations eliminates the possibility that the chance combination of DNA from your father and mother is “appearing” as Native, when it isn’t.

We can use segment information to our benefit, especially if we don’t know exactly who contributed that DNA – meaning which ancestor.

We need to find a way to utilize those Native or other minority segments genealogically.

23andMe

Today, the only DNA testing vendor that provides consumers with a segment identification of our ethnicity predictions is 23andMe.

If you have tested at 23andMe, sign in and click on Ancestry on the top tab, then select Ancestry Composition.

Minority ethnicity ancestry composition.png

Scroll down until you see your painted chromosomes.

Minority ethnicity chromosome painting.png

By clicking on the region at left that you want to see, the rest of the regions are greyed out and only that region is displayed on your chromosomes, at right.

Minority ethnicity Native.png

According to 23andMe, I have two Native segments, one each on chromosomes 1 and 2. They show these segments on opposite chromosomes, meaning one (the top for example) would be maternal or paternal, and the bottom one would be the opposite. But 23andMe apparently could not tell for sure because neither my mother nor father have tested there. This placement also turned out to be incorrect. The above image was my initial V3 test at 23andMe. My later V4 results were different.

Versions May Differ

Please note that your ethnicity predictions may be different based on which test you took which is dictated by when you took the test. The image above is my V3 test that was in use at 23andMe between 2010 and November 2013, and the image below is my V4 test in use between November 2013 and August 2017.

23andMe apparently does not correct original errors involving what is known as “strand swap” where the maternal and paternal segments are inverted during analysis. My V4 test results are shown below, where the strands are correctly portrayed.

Minority ethnicity Native V4.png

Note that both Native segments are now on the lower chromosome “side” of the pair and the position on the chromosome 1 segment has shifted visually.

Minority ethnicity sides.png

I have not tested at 23andMe on the current V5 GSA chip, in use since August 9, 2017, but perhaps I should. The results might be different yet, with the concept being that each version offers an improvement over earlier versions as science advances.

If your parents have tested, 23andMe makes adjustments to your ethnicity estimates accordingly.

Although my mother can’t test at 23andMe, I happen to already know that these Native segments descend from my mother based on genealogical and genetic analysis, combined. I’m going to walk you through the process.

I can utilize my genealogy to confirm or refute information shown by 23andMe. For example, if one of those segments comes from known ancestors who were living in Germany, it’s clearly not Native, and it’s noise of some type.

We’re going to utilize DNAPainter to determine which ancestors contributed your minority segments, but first you’ll need to download your ethnicity segments from 23andMe.

Downloading Ethnicity Segment Data

Downloading your ethnicity segments is NOT THE SAME as downloading your raw DNA results to transfer to another vendor. Those are two entirely different files and different procedures.

To download the locations of your ethnicity segments at 23andMe, scroll down below your painted ethnicity segments in your Ancestry Composition section to “View Scientific Details.”

MInority ethnicity scientific details.png

Click on View Scientific Details and scroll down to near the bottom and then click on “Download Raw Data.” I leave mine at the 50% confidence level.

Minority ethnicity download raw data.png

Save this spreadsheet to your computer in a known location.

In the spreadsheet, you’ll see columns that provide the name of the segment, the chromosome copy number (1 or 2) and the chromosome number with start and end locations.

Minority ethnicity download.png

You really don’t care about this information directly, but DNAPainter does and you’ll care a lot about what DNAPainter does for you.

DNAPainter

I wrote introductory articles about DNAPainter:

If you’re not familiar with DNAPainter, you might want to read these articles first and then come back to this point in this article.

Go ahead – I’ll wait!

Getting Started

If you don’t have a DNAPainter account, you’ll need to create one for free. Some features, such as having multiple profiles are subscription based, but the functionality you’ll need for one profile is free.

I’ve named this example profile “Ethnicity Demo.” You’ll see your name where mine says “Ethnicity Demo.”

Minority ethnicity DNAPainter.png

Click on “Import 23andme ancestry composition.”

You will copy and paste all the spreadsheet rows in the entire downloaded 23andMe ethnicity spreadsheet into the DNAPainter text box and make your selection, below. The great news is that if you discover that your assumption about copy 1 being maternal or paternal is incorrect, it’s easy to delete the ethnicity segments entirely and simply repaint later. Ditto if 23andMe changes your estimate over time, like they have mine.

Minority ethnicity DNAPainter sides.png

I happen to know that “copy 2” is maternal, so I’ve made that selection.

You can then see your ethnicity chromosome segments painted, and you can expand each one to see the detail. Click on “Save Segments.”

MInority ethnicity DNAPainter Native painting

Click to enlarge

In this example, you can see my Native segments, called by various names at different confidence levels at 23andMe, on chromosome 1.

Depending on the confidence level, these segments are called some mixture of:

  • East Asian & Native American
  • North Asian & Native American
  • Native American
  • Broadly East Asian & Native American

It’s exactly the same segment, so you don’t really care what it’s called. DNAPainter paints all of the different descriptions provided by 23andMe, at all confidence levels as you can see above.

The DNAPainter colors are different from 23andMe colors and are system-selected. You can’t assign the colors for ethnicity segments.

Now, I’m moving to my own profile that I paint with my ancestral segments. To date, I have 78% of my segments painted by identifying cousins with known common ancestors.

On chromosomes 1 and 2, copy 2, which I’ve determined to be my mother’s “side,” these segments track back to specific ancestors.

Minority ethnicity maternal side

Click to enlarge

Chromosome 1 segments, above, track back to the Lore family, descended from Antoine (Anthony) Lore (Lord) who married Rachel Hill. Antoine Lore was Acadian.

Minority ethnicity chromosome 1.png

Clicking on the green segment bar shows me the ancestors I assigned when I painted the match with my Lore family member whose name is blurred, but whose birth surname was Lore.

The Chromosome 2 segment, below, tracks back to the same family through a match to Fred.

Minority ethnicity chromosome 2.png

My common ancestors with Fred are Honore Lore and Marie Lafaille who are the parents of Antoine Lore.

Minority ethnicity common ancestor.png

There are additional matches on both chromosomes who also match on portions of the Native segments.

Now that I have a pointer in the ancestral direction that these Native American segments arrived from, what can traditional genealogy and other DNA information tell me?

Traditional Genealogy Research

The Acadian people were a mixture of English, French and Native American. The Acadians settled on the island of Nova Scotia in 1609 and lived there until being driven out by the English in 1755, roughly 6 or 7 generations later.

Minority ethnicity Acadian map.png

The Acadians intermarried with the Mi’kmaq people.

It had been reported by two very qualified genealogists that Philippe Mius, born in 1660, married two Native American women from the Mi’kmaq tribe given the name Marie.

The French were fond of giving the first name of Marie to Native women when they were baptized in the Catholic faith which was required before the French men were allowed to marry the Native women. There were many Native women named Marie who married European men.

Minority ethnicity Native mitochondrial tree

Click to enlarge

This Mius lineage is ancestral to Antoine Lore (Lord) as shown on my pedigree, above.

Mitochondrial DNA has revealed that descendants from one of Philippe Mius’s wives, Marie, carry haplogroup A2f1a.

However, mitochondrial tests of other descendants of “Marie,” his first wife, carry haplogroup X2a2, also Native American.

Confusion has historically existed over which Marie is the mother of my ancestor, Francoise.

Karen Theroit Reader, another professional genealogist, shows Francoise Mius as the last child born to the first Native wife before her death sometime after 1684 and before about 1687 when Philippe remarried.

However, relative to the source of Native American segments, whether Francoise descends from the first or second wife doesn’t matter in this instance because both are Native and are proven so by their mitochondrial DNA haplogroups.

Additionally, on Antoine’s mother’s side, we find a Doucet male, although there are two genetic male Doucet lines, one of European origin, haplogroup R-L21, and one, surprisingly, of Native origin, haplogroup C-P39. Both are proven by their respective haplogroups but confusion exists genealogically over who descends from which lineage.

On Antoine’s mother’s side, there are several unidentified lineages, any one or multiples of which could also be Native. As you can see, there are large gaps in my tree.

We do know that these Native segments arrived through Antoine Lore and his parents, Honore Lore and Marie LaFaille. We don’t know exactly who upstream contributed these segments – at least not yet. Painting additional matches attributable to specific ancestral couples will eventually narrow the candidates and allow me to walk these segments back in time to their rightful contributor.

Segments, Traditional Research and DNAPainter

These three tools together, when using continent-level segments in combination with painting the DNA segments of known cousins that match specific lineages create a triangulated ethnicity segment.

When that segment just happens to be genealogically important, this combination can point the researchers in the right direction knowing which lines to search for that minority ancestor.

If your cousins who match you on this segment have also tested with 23andMe, they should also be identified as Native on this same segment. This process does not apply to intracontinental segments, meaning within Europe, because the admixture is too great and the ethnicity predictions are much less reliable.

When identifying minority admixture at the continental level, adding Y and mitochondrial DNA testing to the mix in order to positively identify each individual ancestor’s Y and mitochondrial DNA is very important in both eliminating and confirming what autosomal DNA and genealogy records alone can’t do. The base haplogroup as assigned at 23andMe is a good start, but it’s not enough alone. Plus, we only carry one line of mitochondrial DNA and only males carry Y DNA, and only their direct paternal line.

We need Y and mitochondrial DNA matching at FamilyTreeDNA to verify the specific lineage. Additionally, we very well may need the Y and mitochondrial DNA information that we don’t directly carry – but other cousins do. You can read about Y and mitochondrial DNA testing, here.

I wrote about creating a personal DNA pedigree chart including your ancestors’ Y and mitochondrial DNA here. In order to find people descended from a specific ancestor who have DNA tested, I utilize:

  • WikiTree resources and trees
  • Geni trees
  • FamilySearch trees
  • FamilyTreeDNA autosomal matches with trees
  • AncestryDNA autosomal matches and their associated trees
  • Ancestry trees in general, meaning without knowing if they are related to a DNA match
  • MyHeritage autosomal matches and their trees
  • MyHeritage trees in general

At both MyHeritage and Ancestry, you can view the trees of your matches, but you can also search for ancestors in other people’s trees to see who might descend appropriately to provide a Y or mitochondrial DNA sample. You will probably need a subscription to maximize these efforts. My Heritage offers a free trial subscription here.

If you find people appropriately descended through WikiTree, Geni or FamilySearch, you’ll need to discuss DNA testing with them. They may have already tested someplace.

If you find people who have DNA tested through your DNA matches with trees at Ancestry and MyHeritage, you’ll need to offer a Y or mitochondrial DNA test to them if they haven’t already tested at FamilyTreeDNA.

FamilyTreeDNA is the only vendor who provides the Y DNA and mitochondrial DNA tests at the higher resolution level, beyond base haplogroups, required for matching and for a complete haplogroup designation.

If the person has taken the Family Finder autosomal test at FamilyTreeDNA, they may have already tested their Y DNA and mtDNA, or you can offer to upgrade their test.

Projects

Checking projects at FamilyTreeDNA can be particularly useful when trying to discover if anyone from a specific lineage has already tested. There are many, special interest projects such as the Acadian AmerIndian Ancestry project, the American Indian project, haplogroup projects, surname projects and more.

You can view projects alphabetically here or you can click here to scroll down to enter the surname or topic you are seeking.

Minority ethnicity project search.png

If the topic isn’t listed, check the alphabetic index under Geographical Projects.

23andMe Maternal and Paternal Sides

If possible, you’ll want to determine which “side” of your family your minority segments originate come from, unless they come from both. you’ll want to determine whether chromosome side one 1 or 2 is maternal, because the other one will be paternal.

23andMe doesn’t offer tree functionality in the same way as other vendors, so you won’t be able to identify people there descended from your ancestors without contacting each person or doing other sleuthing.

Recently, 23andMe added a link to FamilySearch that creates a list of your ancestors from their mega-shared tree for 7 generations, but there is no tree matching or search functionality. You can read about the FamilySearch connection functionality here.

So, how do you figure out which “side” is which?

Minority ethnicity minority segment.png

The chart above represents the portion of your chromosomes that contains your minority ancestry. Initially, you don’t know if the minority segment is your mother’s pink chromosome or your father’s blue chromosome. You have one chromosome from each parent with the exact same addresses or locations, so it’s impossible to tell which side is which without additional information. Either the pink or the blue segment is minority, but how can you tell?

In my case, the family oral history regarding Native American ancestry was from my father’s line, but the actual Native segments wound up being from my mother, not my father. Had I made an assumption, it would have been incorrect.

Fortunately, in our example, you have both a maternal and paternal aunt who have tested at 23andMe. You match both aunts on that exact same segment location – one from your father’s side, blue, and one from your mother’s side, pink.

You compare your match with your maternal aunt and verify that indeed, you do match her on that segment.

You’ll want to determine if 23andMe has flagged that segment as Native American for your maternal aunt too.

You can view your aunt’s Ancestry Composition by selecting your aunt from the “Your Connections” dropdown list above your own ethnicity chromosome painting.

Minority ethnicity relative connections.png

You can see on your aunt’s chromosomes that indeed, those locations on her chromosomes are Native as well.

Minority ethnicity relative minority segments.png

Now you’ve identified your minority segment as originating on your maternal side.

Minority ethnicity Native side.png

Let’s say you have another match, Match 1, on that same segment. You can easily tell which “side” Match 1 is from. Since you know that you match your maternal aunt on that minority segment, if Match 1 matches both you and your maternal aunt, then you know that’s the side the match is from – AND that person also shares that minority segment.

You can also view that person’s Ancestry Composition as well, but shared matching is more reliable,especially when dealing with small amounts of minority admixture.

Another person, Match 2, matches you on that same segment, but this time, the person matches you and your paternal aunt, so they don’t share your minority segment.

Minority ethnicity match side.png

Even if your paternal aunt had not tested, because Match 2 does not match you AND your maternal aunt, you know Match 2 doesn’t share your minority segment which you can confirm by checking their Ancestry Composition.

Download All of Your Matches

Rather than go through your matches one by one, it’s easiest to download your entire match list so you can see which people match you on those chromosome locations.

Minority ethnicity download aggregate data.png

You can click on “Download Aggregate Data” at 23andMe, at the bottom of your DNA Relatives match list to obtain all of your matches who are sharing with you. 23andMe limits your matches to 2000 or less, the actual number being your highest 2000 matches minus the people who aren’t sharing. I have 1465 matches showing and that number decreases regularly as new testers at 23andMe are focused on health and not genealogy, meaning lower matches get pushed off the list of 2000 match candidates.

You can quickly sort the spreadsheet to see who matches you on specific segments. Then, you can check each match in the system to see if that person matches you and another known relative on the minority segments or you can check their Ancestry Composition, or both.

If they share your minority segment, then you can check their tree link if they have one, included in the download, their Family Search information if included on their account, or reach out to them to see if you might share a known ancestor.

The key to making your ethnicity segment work for you is to identify ancestors and paint known matches.

Paint Those Matches

When searching for matches whose DNA you can attribute to specific ancestors, be sure to check at all 4 places that provide segment information that you can paint:

At GedMatch, you’ll find some people who have tested at the other various vendors, including Ancestry, but unfortunately not everyone uploads. Ancestry doesn’t provide segment information, so you won’t be able to paint those matches directly from Ancestry.

If your Ancestry matches transfer to GedMatch, FamilyTreeDNA or MyHeritage you can view your match and paint your common segments. At GedMatch, Ancestry kit numbers begin with an A. I use my Ancestry kit matches at GedMatch to attempt to figure out who that match is at Ancestry in order to attempt to figure out the common ancestor.

To Paint, You Must Test

Of course, in order to paint your matches that you find in various databases, you need to be in those data bases, meaning you either need to test there or transfer your DNA file.

Transfers

If you’d like to test your DNA at one vendor and download the file to transfer to another vendor, or GedMatch, that’s possible with both FamilyTreeDNA and MyHeritage who both accept uploads.

You can transfer kits from Ancestry and 23andMe to both FamilyTreeDNA and MyHeritage for free, although the chromosome browsers, advanced tools and ethnicity require an unlock fee (or alternatively a subscription at MyHeritage). Still, the free transfer and unlock for $19 at FamilyTreeDNA or $29 at MyHeritage is less than the cost of testing.

Here’s a quick cheat sheet.

DNA vendor transfer cheat sheet 2019

From time to time, as vendor file formats change, the ability to transfer is temporarily interrupted, but it costs nothing to try a transfer to either MyHeritage or FamilyTreeDNA, or better yet, both.

In each of these articles, I wrote about how to download your data from a specific vendor and how to upload from other vendors if they accept uploads.

Summary Steps

In order to use your minority ethnicity segments in your genealogy, you need to:

  1. Test at 23andMe
  2. Identify which parental side your minority ethnicity segments are from, if possible
  3. Download your ethnicity segments
  4. Establish a DNAPainter account
  5. Upload your ethnicity segments to DNAPainter
  6. Paint matches of people with whom you share known common ancestors utilizing segment information from 23andMe, FamilyTreeDNA, MyHeritage and AncestryDNA matches who have uploaded to GedMatch
  7. If you have not tested at either MyHeritage or FamilyTreeDNA, upload your 23andMe file to either vendor for matching, along with GedMatch
  8. Focus on those minority segments to determine which ancestral line they descend through in order to identify the ancestor(s) who provided your minority admixture.

Have fun!

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