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

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

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

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

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

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

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

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

Let’s go!

The Step-by-Step Educational Answer😊

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

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

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

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

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

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

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

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

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

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

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

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

Let’s start by dispelling a myth.

DNA Doesn’t Skip Generations!

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

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

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

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

Full stop.

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

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

DNA skipping generations is a fallacy.

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

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

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

We’ll talk about that more in a minute.

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

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

Legitimate Matches

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

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

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

Thankfully, there are ways to tell the difference.

Inheritance and Triangulation

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

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

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

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

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

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

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

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

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

This is exactly why triangulation works and is crucial.

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

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

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

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

This is the first step in identifying false matches.

Parental Cross-Matching

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Parental Phasing

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

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

See how easy that was!

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

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

There are four possible match conditions:

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

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

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

Automatic Phasing at FamilyTreeDNA

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

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

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

Parental Phasing Caveats

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

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

Let’s take a look at that.

Pedigree Collapse

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

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

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

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

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

Let’s look at another example.

click to enlarge image

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

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

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

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

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

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

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

Endogamy

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

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

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

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

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

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

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

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

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

Your Parents Have DNA That You Don’t

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Let’s analyze this a bit further.

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

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

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

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

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

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

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

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

Imputation

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

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

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

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

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

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

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

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

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

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

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

Imputation is actually MUCH less problematic than I initially expected.

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

How can we minimize the effects of imputation?

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

Additionally, Ancestry has a few complicating factors.

Ancestry Issues

AncestryDNA is different in three ways.

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

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

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

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

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

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

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

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

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

Ancestry WorkArounds

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

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

I wrote about Triangulation in Action at FamilyTreeDNA, here.

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

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

I wrote about Triangulation in Action at MyHeritage, here.

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

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

I wrote about Triangulation in Action at GEDmatch, here.

Transferring/Uploading Your DNA 

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

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

Testing Close Relatives Is VERY Useful – Just Not for Triangulation

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

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

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

Ok, back to triangulation.

Triangulated Matches

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

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

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

“It depends.”

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

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

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

Let’s explore some examples.

Building Triangulation Evidence – Ingredients and a Recipe

The strongest case of triangulation is when:

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

Let’s look at a valid triangulated match.

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

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

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

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

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

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

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

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

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

Click to enlarge image

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

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

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

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

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

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

Aunts and Uncles

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

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

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

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

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

Ok, then, what about siblings?

Siblings

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

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

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

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

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

How False Positives Work and How to Avoid Them

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Distant Cousins Are Best for Triangulation & Here’s Why

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

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

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

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

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

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

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

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

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

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

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

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

Whew!!!

The Bottom Line

Here’s the bottom line.

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

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

Have fun!!!

_____________________________________________________________

Disclosure

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

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Products and Services

Books

Genealogy Research

Haplogroup Matching: What It Does (and Doesn’t) Mean

“Our haplogroups (sort of) match, so that means we’re related, right?”

Well, maybe.

It depends.

Great Question

This is an oft-asked great question. Of course, the answer varies depending on the context of the question and what is meant by “related.” A haplogroup match may or may not be a valid match for genealogy. A “match” or a “not match” can mean different things.

The questions people often ask include:

  • Does a haplogroup have to match exactly in order for another person to either be considered a match to you?
  • If they don’t match exactly, can they still be considered as a possible match?
  • Conversely, can we rule someone out as a match on a specific genealogical line based on haplogroup alone?

These questions often arise in relation to DNA testing at Family Tree DNA, sometimes when people are trying to compare results to people who have haplogroup estimates, either at FamilyTreeDNA or from testing elsewhere.

In other words, if one person is haplogroup J and someone else is J1, either at the same vendor or at another, what does that tell us? This question pertains to both Y DNA and mitochondrial DNA tests no matter where you’ve tested.

Family Tree DNA offers different levels of Y DNA testing. Interpreting those match results can sometimes be confusing. The same is true for mitochondrial DNA, especially if your matches have not taken the full mitochondrial sequence (mtFull) test.

You might be comparing apples and oranges, or you might be comparing a whole orange (detailed test) with a few slices (haplogroup estimate.) How can you know, and how can you make sense of the results?

If you’re comparing a haplogroup between sources, such as a partial haplogroup determined by testing through a company like 23andMe or LivingDNA to complete tests taken at FamilyTreeDNA, the answer can be less than straightforward.

I discussed the difference between autosomal-based haplogroup assignments and actual testing of both Y DNA and mitochondrial DNA which result in haplogroup assignments, here. In a nutshell, both LivingDNA and 23andMe provide a high-level (base) haplogroup estimates based on a few specific probes when you purchase an autosomal test, but that’s not the same as deeper testing of the Y chromosome or mitochondrial DNA.

The answer to whether your haplogroup has to match is both “yes”, and “no.” Don’t you hate it when this happens?

Let’s look at different situations. But to begin with, there is at least one common answer.

Yes, Your Base Haplogroup Must Match

To even begin to look further for a common ancestor on either your Y DNA line (direct patrilineal) or direct mitochondrial matrilineal line (your mother’s mother’s mother’s line on up the tree), your base haplogroup much match.

In other words, you and your matches must all be in the same base haplogroup. Haplogroups are defined by the presence of specific combinations of mutations which are called SNPs (single nucleotide polymorphisms) in the Y DNA.

Click to enlarge images

All of these men on the Y DNA matches page are a branch of haplogroup R as shown under the Y-DNA Haplogroup column. There are more matches on down the page (not shown here) with more and different haplogroups. However, you’ll notice that all matches are a subset of haplogroup R, the base haplogroup.

The same is true for mitochondrial DNA haplogroups. You can see in this example that people who have not tested at the FMS (full mitochondrial sequence) level have a less specific haplogroup. The entire mitochondria must be tested in order to obtain a full haplogroup, such as J1c2f, as opposed to haplogroup J.

The Y DNA Terminal SNP Might Not Match

For Y DNA testers, when looking at your matches, even to close relatives, you may not have the same exact haplogroup because:

  • Some people may have tested at different levels
  • Some people in recent generations may have developed a SNP specific to their line.

In other words, haplogroups, testing level, and known genealogy all need to be considered, especially when the haplogroups are “close to each other” on the tree.

For Y DNA, FamilyTreeDNA:

  • Provides all testers with base haplogroup estimates based on STR tests, meaning 12-111 marker panels. These are very accurate estimates, but are also very high level.
  • Offers or has offered in the past both individual SNP tests and SNP packs or bundles that test individual SNPs indicating their presence or absence. This confirms a SNP or haplogroup, but only to that particular level.
  • Offers the Big Y-700 test, along with upgrades to previous Big Y test levels. There have been 3 versions of the Big Y test over time. The Big Y reads the entire gold standard region of the Y chromosome, reporting the known (named) SNP mutations customers do and don’t have. Additionally, the test reports any unnamed SNPs which are considered private variants until multiple men on the same branch of the Y DNA tree test with the same mutation. At that point, the mutation is named and becomes a haplogroup.

That’s why the answer is “no,” your haplogroup does not have to match exactly for you to actually be a match to each other.

A father and son could test, with one having an estimated haplogroup of R-M269 and the other taking the Big Y-700 resulting in a very different Terminal SNP, quite distant on the tree. Conversely, both men could take the Big Y and the son could have a different terminal SNP than the father because a mutation occurred between them. An autosomal DNA test would confirm that they are in fact, father and son.

However, a father and son who test and are placed in different base haplogroups – one in haplogroup I, and the other in haplogroup R, for example, has a very different situation. Their autosomal test would likely confirm that they are not father and son.

Having said this about paternity, especially if haplogroups are estimated and specific Y DNA SNP testing has not been done, don’t have a premature freak-out moment. Look at autosomal DNA, assuming you DO want to know. Y DNA alone should never be used to infer paternity without autosomal testing.

Let’s look at some examples.

Matches and Haplogroups

In the example shown above, you can see that several people have taken the Big Y test, so their SNP will be shown on further down the haplotree than those testers who have not. These are a leaf, not a branch.

You can see by looking at the Terminal SNP column, at far right, that people who have either taken the Big Y, or had any positive SNP test will have a value in the Terminal SNP column.

Anyone who has NOT taken the Big Y or taken a SNP test will have their base haplogroup estimated based on their STR tests. In this case, that estimate is R-M269. People with estimated haplogroups will not show anything in the Terminal SNP column.

It’s possible that if all of these men took the Big Y test that at least some would share the same Terminal SNP, and others might be closely related, only a branch or so different on the tree.

These men in this example are all descendants of Robert Estes born in England in 1555. All have Estes surnames, except for one man who is seeking the identity of his paternal line.

Let’s Look at the Tree

Our tester in the screenshot is haplogroup R-ZS3700 and matches men in the following haplogroups:

  • R-M269
  • R-L21
  • R-BY490
  • R-BY154784

There are a few additional haplogroups not shown because they are further down on his match list, so let’s just work with these for now.

After determining that these men are on the same branch of the Y tree, haplogroup R, the real question is how closely they are related and how close or far distant their terminal SNPs are located. More distance means the common ancestor is further back in time.

However, looks can be deceiving, especially if not everyone has tested to the same level.

The haplogroup furthest up in the tree, meaning the oldest, is R-M269, followed by the man who took the single SNP test for R-L21. Notice that R-M269 has more than 15,000 branches, so while this haplogroup could be used to rule out a match, R-M269 alone isn’t useful to determine genealogical matching.

There are a lot of branches between R-L21 and the next haplogroup on the tree.

Finally, here we go. Our tester is haplogroup R-ZS3700 that has one descendant branch. R-ZS3700 is a branch of R-BY490 that has 2 branches.

R-BY154784 is the last SNP on this branch of the tree. Our tester matches this man too.

Another way of viewing these matches is on the Block Tree provided for Big Y testers.

In this view, you can see that the Estes men all match back to about 18 “SNP generations” ago according to the legend at left, but they don’t match men further back in time who have taken the Big Y test.

Notice the up-arrow where haplogroups R-L21 and R-M269 are shown across the top of the display.

If you click on R-L21, you’ll see that that it appears about 61 SNP generations back in time.

Haplogroup R-M269 appears even further back in time, about 174 SNP generations.

The only reason you will match someone at either the R-L21 or R-M269 level is because you both descend from a common long-ago ancestral branch, hundreds to thousands of years in the past. You and they would both need to take either the Big Y-700 test for Y DNA, or the full sequence mitochondrial DNA test in order to determine your full haplogroup and see your list of matches based on those full sequences.

Public Trees

You can view FamilyTreeDNA‘s extensive public Y DNA tree by haplogroup, here.

You can view their public mitochondrial DNA tree by haplogroup, here.

And the Answer Is…

As you can see, there is no single answer to the question of haplogroup relationships. The answer is also partly defined by the context in which the question is asked.

  1. For two men to be “related” on the Y DNA patrilineal line, yes, minimally, the base haplogroup does have to match. Base haplogroups are defined by the leading letter, like “R” in the examples above.
  2. “Related” based on base haplogroup only can be hundreds or thousands of years back in time, but additional testing can resolve that question.
  3. “Related” can mean before the advent of surnames. However, a match to a man with the same surname suggests a common ancestor with that surname in the past several hundred years. That match could, however, be much closer in time.
  4. For two men to be closely related, assuming they have taken the same version of Big Y test, their haplogroup branches need to be fairly closely adjacent on the haplotree. FamilyTreeDNA will be introducing haplogroup aging soon, meaning SNP/haplogroup branch dates on their haplotree. At that time, the “distance” between men will be easier to understand.
  5. You can exclude a genealogical relationship on the direct paternal line if the two men involved have a different base haplogroup. This question often occurs when people are trying to understand if they “might match” with someone whose haplogroup has been estimated.
  6. This holds true as well for mitochondrial DNA haplogroups and matching.

And there you have it, six answers about what haplogroup matching does and does not mean.

The bottom line is that haplogroups can be a great starting point and you can sometimes eliminate people as potential matches.

However, to confirm genealogical matches, you’ll always need more granular testing that includes actual Y DNA or mitochondrial DNA matching based on marker mutation results, not just haplogroups.

_____________________________________________________________

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

Books

Y DNA Resources and Repository

I’ve created a Y DNA resource page with the information in this article, here, as a permanent location where you can find Y DNA information in one place – including:

  • Step-by-step guides about how to utilize Y DNA for your genealogy
  • Educational articles and links to the latest webinars
  • Articles about the science behind Y DNA
  • Ancient DNA
  • Success stories

Please feel free to share this resource or any of the links to individual articles with friends, genealogy groups, or on social media.

If you haven’t already taken a Y DNA test, and you’re a male (only males have a Y chromosome,) you can order one here. If you also purchase the Family Finder, autosomal test, those results can be used to search together.

What is Y DNA?

Y DNA is passed directly from fathers to their sons, as illustrated by the blue arrow, above. Daughters do not inherit the Y chromosome. The Y chromosome is what makes males, male.

Every son receives a Y chromosome from his father, who received it from his father, and so forth, on up the direct patrilineal line.

Comparatively, mitochondrial DNA, the pink arrow, is received by both sexes of children from the mother through the direct matrilineal line.

Autosomal DNA, the green arrow, is a combination of randomly inherited DNA from many ancestors that is inherited by both sexes of children from both parents. This article explains a bit more.

Y DNA has Unique Properties

The Y chromosome is never admixed with DNA from the mother, so the Y chromosome that the son receives is identical to the father’s Y chromosome except for occasional minor mutations that take place every few generations.

This lack of mixture with the mother’s DNA plus the occasional mutation is what makes the Y chromosome similar enough to match against other men from the same ancestors for hundreds or thousands of years back in time, and different enough to be useful for genealogy. The mutations can be tracked within extended families.

In western cultures, the Y chromosome path of inheritance is usually the same as the surname, which means that the Y chromosome is uniquely positioned to identify the direct biological patrilineal lineage of males.

Two different types of Y DNA tests can be ordered that work together to refine Y DNA results and connect testers to other men with common ancestors.

FamilyTreeDNA provides STR tests with their 37, 67 and 111 marker test panels, and comprehensive STR plus SNP testing with their Big Y-700 test.

click to enlarge

STR markers are used for genealogy matching, while SNP markers work with STR markers to refine genealogy further, plus provide a detailed haplogroup.

Think of a haplogroup as a genetic clan that tells you which genetic family group you belong to – both today and historically, before the advent of surnames.

This article, What is a Haplogroup? explains the basic concept of how haplogroups are determined.

In addition to the Y DNA test itself, Family Tree DNA provides matching to other testers in their database plus a group of comprehensive tools, shown on the dashboard above, to help testers utilize their results to their fullest potential.

You can order or upgrade a Y DNA test, here. If you also purchase the Family Finder, autosomal test, those results can be used to search together.

Step-by-Step – Using Your Y DNA Results

Let’s take a look at all of the features, functions, and tools that are available on your FamilyTreeDNA personal page.

What do those words mean? Here you go!

Come along while I step through evaluating Big Y test results.

Big Y Testing and Results

Why would you want to take a Big Y test and how can it help you?

While the Big Y-500 has been superseded by the Big Y-700 test today, you will still be interested in some of the underlying technology. STR matching still works the same way.

The Big Y-500 provided more than 500 STR markers and the Big Y-700 provides more than 700 – both significantly more than the 111 panel. The only way to receive these additional markers is by purchasing the Big Y test.

I have to tell you – I was skeptical when the Big Y-700 was introduced as the next step above the Big Y-500. I almost didn’t upgrade any kits – but I’m so very glad that I did. I’m not skeptical anymore.

This Y DNA tree rocks. A new visual format with your matches listed on their branches. Take a look!

Educational Articles

I’ve been writing about DNA for years and have selected several articles that you may find useful.

What kinds of information are available if you take a Y DNA test, and how can you use it for genealogy?

What if your father isn’t available to take a DNA test? How can you determine who else to test that will reveal your father’s Y DNA information?

Family Tree DNA shows the difference in the number of mutations between two men as “genetic distance.” Learn what that means and how it’s figured in this article.

Of course, there were changes right after I published the original Genetic Distance article. The only guarantees in life are death, taxes, and that something will change immediately after you publish.

Sometimes when we take DNA tests, or others do, we discover the unexpected. That’s always a possibility. Here’s the story of my brother who wasn’t my biological brother. If you’d like to read more about Dave’s story, type “Dear Dave” into the search box on my blog. Read the articles in publication order, and not without a box of Kleenex.

Often, what surprise matches mean is that you need to dig further.

The words paternal and patrilineal aren’t the same thing. Paternal refers to the paternal half of your family, where patrilineal is the direct father to father line.

Just because you don’t have any surname matches doesn’t necessarily mean it’s because of what you’re thinking.

Short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs) aren’t the same thing and are used differently in genealogy.

Piecing together your ancestor’s Y DNA from descendants.

Haplogroups are something like our pedigree charts.

What does it mean when you have a zero for a marker value?

There’s more than one way to break down that brick wall. Here’s how I figured out which of 4 sons was my ancestor.

Just because you match the right line autosomally doesn’t mean it’s because you descend from the male child you think is your ancestor. Females gave their surnames to children born outside of a legal marriage which can lead to massive confusion. This is absolutely why you need to test the Y DNA of every single ancestral line.

When the direct patrilineal line isn’t the line you’re expecting.

You can now tell by looking at the flags on the haplotree where other people’s ancestral lines on your branch are from. This is especially useful if you’ve taken the Big Y test and can tell you if you’re hunting in the right location.

If you’re just now testing or tested in 2018 or after, you don’t need to read this article unless you’re interested in the improvements to the Big Y test over the years.

2019 was a banner year for discovery. 2020 was even more so, keeping up an amazing pace. I need to write a 2020 update article.

What is a terminal SNP? Hint – it’s not fatal😊

How the TIP calculator works and how to best interpret the results. Note that this tool is due for an update that incorporates more markers and SNP results too.

You can view the location of the Y DNA and mitochondrial DNA ancestors of people whose ethnicity you match.

Tools and Techniques

This free public tree is amazing, showing locations of each haplogroup and totals by haplogroup and country, including downstream branches.

Need to search for and find Y DNA candidates when you don’t know anyone from that line? Here’s how.

Yes, it’s still possible to resolve this issue using autosomal DNA. Non-matching Y DNA isn’t the end of the road, just a fork.

Science Meets Genealogy – Including Ancient DNA

Haplogroup C was an unexpected find in the Americas and reaches into South America.

Haplogroup C is found in several North American tribes.

Haplogroup C is found as far east as Nova Scotia.

Test by test, we made progress.

New testers, new branches. The research continues.

The discovery of haplogroup A00 was truly amazing when it occurred – the base of the phylotree in Africa.

The press release about the discovery of haplogroup A00.

In 2018, a living branch of A00 was discovered in Africa, and in 2020, an ancient DNA branch.

Did you know that haplogroups weren’t always known by their SNP names?

This brought the total of SNPs discovered by Family Tree DNA in mid-2018 to 153,000. I should contact the Research Center to see how many they have named at the end of 2020.

An academic paper split ancient haplogroup D, but then the phylogenetic research team at FamilyTreeDNA split it twice more! This might not sound exciting until you realize this redefines what we know about early man, in Africa and as he emerged from Africa.

Ancient DNA splits haplogroup P after analyzing the remains of two Jehai people from West Malaysia.

For years I doubted Kennewick Man’s DNA would ever be sequenced, but it finally was. Kennewick Man’s mitochondrial DNA haplogroup is X2a and his Y DNA was confirmed to Q-M3 in 2015.

Compare your own DNA to Vikings!

Twenty-seven Icelandic Viking skeletons tell a very interesting story.

Irish ancestors? Check your DNA and see if you match.

Ancestors from Hungary or Italy? Take a look. These remains have matches to people in various places throughout Europe.

The Y DNA story is no place near finished. Dr. Miguel Vilar, former Lead Scientist for National Geographic’s Genographic Project provides additional analysis and adds a theory.

Webinars

Y DNA Webinar at Legacy Family Tree Webinars – a 90-minute webinar for those who prefer watching to learn! It’s not free, but you can subscribe here.

Success Stories and Genealogy Discoveries

Almost everyone has their own Y DNA story of discovery. Because the Y DNA follows the surname line, Y DNA testing often helps push those lines back a generation, or two, or four. When STR markers fail to be enough, we can turn to the Big Y-700 test which provides SNP markers down to the very tip of the leaves in the Y DNA tree. Often, but not always, family-defining SNP branches will occur which are much more stable and reliable than STR mutations – although SNPs and STRs should be used together.

Methodologies to find ancestral lines to test, or maybe descendants who have already tested.

DNA testing reveals an unexpected mystery several hundred years old.

When I write each of my “52 Ancestor” stories, I include genetic information, for the ancestor and their descendants, when I can. Jacob was special because, in addition to being able to identify his autosomal DNA, his Y DNA matches the ancient DNA of the Yamnaya people. You can read about his Y DNA story in Jakob Lenz (1748-1821), Vinedresser.

Please feel free to add your success stories in the comments.

What About You?

You never know what you’re going to discover when you test your Y DNA. If you’re a female, you’ll need to find a male that descends from the line you want to test via all males to take the Y DNA test on your behalf. Of course, if you want to test your father’s line, your father, or a brother through that father, or your uncle, your father’s brother, would be good candidates.

What will you be able to discover? Who will the earliest known ancestor with that same surname be among your matches? Will you be able to break down a long-standing brick wall? You’ll never know if you don’t test.

You can click here to upgrade an existing test or order a Y DNA test.

Share the Love

You can always forward these articles to friends or share by posting links on social media. Who do you know that might be interested?

_____________________________________________________________

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

Books

Most Popular Articles of 2020

We all know that 2020 was a year like no other, right? So, what were we reading this year as we spent more time at home?

According to my blog stats, these are the ten most popular articles of 2020.

2020 Rank Blog Article Name Publication Date/Comment
1 Concepts – Calculating Ethnicity Percentages Jan 11, 2017
2 Proving Native American Ancestry Using DNA December 18, 2012
3 Ancestry to Remove DNA Matches Soon – Preservation Strategies with Detailed Instructions Now obsolete article – July 16, 2020
4 Ancestral DNA Percentages – How Much of Them is in You? June 27, 2017
5 Full or Half Siblings? April 3, 2019
6 442 Ancient Viking Skeletons Hold DNA Surprises – Does Your Y or Mitochondrial DNA Match? September 18, 2020
7 Migration Pedigree Chart March 25, 2016
8 DNA Inherited from Grandparents and Great-Grandparents January 14, 2020
9 Optimizing Your Tree at Ancestry for More Hints and DNA ThruLines February 22, 2020
10 Phylogenetic Tree of Novel Coronavirus (hCoV-19) Covid-19 March 12, 2020

Half of these articles were published this year, and half are older.

One article is now obsolete. The Ancestry purge has already happened, so there’s nothing to be done now.

Let’s take a look at the rest and what messages might be held in these popular selections.

Ethnicity

I’m not the least bit surprised by ethnicity being the most popular topic, nor that Concepts – Calculating Ethnicity Percentages is the most popular article. Not only is ethnicity a perennially favorite, but all four major vendors introduced something new this year.

By the way, my perennial caveat still applies – ethnicity is only an estimate😊

While Genetic Groups isn’t actually ethnicity, per se, it’s a layer on top of ethnicity that provides you with locations where your ancestors might have been from and migrated to, based on genetic clusters. Clusters are defined by the locations of ancestors of other people within that genetic cluster.

There’s actually good news at 23andMe. Since this article was published in October, 23andMe has indeed updated the V3 and V4 kits with new ethnicity updates. 23andMe had originally stated they weren’t going to do that, clearly in the hope that people would pay to retest by purchasing the V5 Health + Ancestry test. I’m so glad to see their reversal.

Viewing the older V2 kits, the “updated” date at the bottom of their Ancestry Composition page says they were updated on December 9th or 10th, but I don’t see a difference and they don’t have the “updated” icon like the V3 and V4 kits do.

23andMe made another reversal too and also restored the original matches. They had reduced the number of matches to 1500 for non-Health+Ancestry testers who don’t also subscribe. If you wanted between 1500 and 5000 matches, you had to retest and subscribe for $29 per year. (It’s worth noting that I have over 5000 matches at all of the other vendors.)

To date, 23andMe has restored previous matches and also restored some but not all of the search functionality that they had removed.

What isn’t clear is whether 23andMe will continue to add to this number of matches until the tester reaches the earlier limit of 2000, or whether they have simply restored the previous matches, but the match total will not increase unless you have a subscription.

Consumer feedback works – so thanks to everyone who provided feedback to 23andMe.

Native American Ancestry

The article, Proving Native American Ancestry Using DNA, written 8 years ago, only 5 months after launching this blog, has been in the top 10 every year since I’ve been counting.

I created a Native American reference and resource page too, which you can find here.

I’ll also be publishing some new articles after the first of the year which I promise you’ll find VERY INTERESTING. Something to look forward to.

Understanding Autosomal DNA

2020 has seen more people delving into genealogy + DNA testing which means they need to understand both the results and the concepts underlying their results.

Whooohooo – more people in the pool. Jump on in – the water’s fine!

The articles Ancestral DNA Percentages – How Much of Them is in You? and DNA Inherited from Grandparents and Great-Grandparents both explain how DNA is passed from your ancestors to you.

These are great basic articles if you’re looking to help someone new, and so is First Steps When Your DNA Results are Ready – Sticking Your Toe in the Genealogy Water.

I always look forward to the end of January because there will be lots of matches from holiday gifts being posted. Feel free to forward any of these articles to your new matches. It’s always fun helping new people because you just never know when they might be able to help you.

Surprises

With more and more people testing, more and more people are receiving “surprises” in their results. Need to figure out the difference between full and half-siblings? Then Full or Half Siblings? is the article for you.

Trying to discern other relationships? My favorite tool is the Shared cM Project tool at DNAPainter, here.

Vikings

Who doesn’t want to know if they are related to the ancient Vikings??? You can make that discovery in the article, 442 Ancient Viking Skeletons Hold DNA Surprises – Does Your Y or Mitochondrial DNA Match?. Not only is this just plain fun, but I snuck in a little education too.

Of course, you’ll need to have your Y DNA or mitochondrial DNA results, which you can easily order, here. If you’re unsure and would like to read a short article about the different kinds of DNA and how they can help you, 4 Kinds of DNA for Genetic Genealogy is perfect.

Do you think your DNA isn’t Viking because your ancestors aren’t from Scandinavia? Guess again!

Those Vikings didn’t stay home, and they didn’t restrict their escapades to the British Isles either.

This drawing depicts Viking ships besieging Paris in the year 845. Vikings voyaged into Russia and as far as the Mediterranean.

Have a child studying at home? This might be an interesting topic!

Migration Pedigree Chart

Another just plain fun idea is the Migration Pedigree Chart.

I created this migration pedigree chart in a spreadsheet, but you can also create a pedigree chart in genealogy software with whatever “names” you want. This will also help you figure out the estimated percentages of ethnicity you might reasonably expect.

Another idea for helping kids learn at home and they might accidentally learn about figuring percentages in the process.

ThruLines

ThruLines is the Ancestry tool that assists DNA testers with trees connect the dots to common ancestors with their matches. There are ways to optimize your tree to improve your connections, both in terms of accuracy and the number of Thrulines that form.

Optimizing Your Tree at Ancestry for More Hints and DNA ThruLines provides step by step instructions, which reminds me – I need to write a similar article for MyHeritage’s Theories of Family Relativity. I keep meaning to…

Covid

You know, it wouldn’t be 2020 if I didn’t HAVE to mention that word.

I’m glad to know that people were and hopefully still are educating themselves about Covid. Phylogenetic Tree of Novel Coronavirus (hCoV-19) Covid-19 reflected early information about the novel virus and our first efforts to sequence the DNA. Of course, as expected, just like any other organism, mutations have occurred since then.

Goodness knows, we are all tired of Covid and the resulting safety protocols. Keep on keeping on. We need you on the other side.

Stay home, mask up when you must leave, stay away from other people outside your family that you live with, wash your hands, and get vaccinated as soon as you can.

And until we can all see each other in person again, hopefully, sooner than later, keep on doing genealogy.

Locked in the Library

Be careful what you ask for.

Remember that dream where you’re locked in a library? Remember saying you don’t have enough time for genealogy?

Well, now you are and now you do.

The library is your desk with your computer or maybe your laptop on a picnic table in the yard.

DNA results, matches, and research tools are the books and you’re officially locked in for at least a few more weeks. Free articles like these are your guide.

Hmmm, pandemic isolation doesn’t sound so bad now, does it??

We’ll just rename it “genealogy library lock-in.”

Happy New Year!

What can you discover?

_____________________________________________________________

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

Books

Concepts: Inheritance

Inheritance.

What is it?

How does it work?

I’m not talking about possessions – but about the DNA that you receive from your parents, and their parents.

The reason that genetic genealogy works is because of inheritance. You inherit DNA from your parents in a known and predictable fashion.

Fortunately, we have more than one kind of DNA to use for genealogy.

Types of DNA

Females have 3 types of DNA and males have 4. These different types of DNA are inherited in various ways and serve different genealogical purposes.

Males Females
Y DNA Yes No
Mitochondrial DNA Yes Yes
Autosomal DNA Yes Yes
X Chromosome Yes, their mother’s only Yes, from both parents

Different Inheritance Paths

Different types of DNA are inherited from different ancestors, down different ancestral paths.

Inheritance Paths

The inheritance path for Y DNA is father to son and is inherited by the brother, in this example, from his direct male ancestors shown by the blue arrow. The sister does not have a Y chromosome.

The inheritance path for the red mitochondrial DNA for both the brother and sister is from the direct matrilineal ancestors, only, shown by the red arrow.

Autosomal DNA is inherited from all ancestral lines on both the father’s and mother’s side of your tree, as illustrated by the broken green arrow.

The X chromosome has a slightly different inheritance path, depending on whether you are a male or female.

Let’s take a look at each type of inheritance, how it works, along with when and where it’s useful for genealogy.

Autosomal DNA

Autosomal DNA testing is the most common. It’s the DNA that you inherit from both of your parents through all ancestral lines back in time several generations. Autosomal DNA results in matches at the major testing companies such as FamilyTreeDNA, MyHeritage, Ancestry, and 23andMe where testers view trees or other hints, hoping to determine a common ancestor.

How does autosomal DNA work?

22 autosomes

Every person has two each of 22 chromosomes, shown above, meaning one copy is contributed by your mother and one copy by your father. Paired together, they form the two-sided shape we are familiar with.

For each pair of chromosomes, you receive one from your father, shown with a blue arrow under chromosome 1, and one from your mother, shown in red. In you, these are randomly combined, so you can’t readily tell which piece comes from which parent. Therein lies the challenge for genealogy.

This inheritance pattern is the same for all chromosomes, except for the 23rd pair of chromosomes, at bottom right, which determined the sex of the child.

The 23rd chromosome pair is inherited differently for males and females. One copy is the Y chromosome, shown in blue, and one copy is the X, shown in red. If you receive a Y chromosome from your father, you’re a male. If you receive an X from your father, you’re a female.

Autosomal Inheritance

First, let’s talk about how chromosomes 1-22 are inherited, omitting chromosome 23, beginning with grandparents.

Inheritance son daughter

Every person inherits precisely half of each of their parents’ autosomal DNA. For example, you will receive one copy of your mother’s chromosome 1. Your mother’s chromosome 1 is a combination of her mother’s and father’s chromosome 1. Therefore, you’ll receive ABOUT 25% of each of your grandparents’ chromosome 1.

Inheritance son daughter difference

In reality, you will probably receive a different amount of your grandparent’s DNA, not exactly 25%, because your mother or father will probably contribute slightly more (or less) of the DNA of one of their parents than the other to their offspring.

Which pieces of DNA you inherit from your parents is random, and we don’t know how the human body selects which portions are and are not inherited, other than we know that large pieces are inherited together.

Therefore, the son and daughter won’t inherit the exact same segments of the grandparents’ DNA. They will likely share some of the same segments, but not all the same segments.

Inheritance maternal autosomalYou’ll notice that each parent carries more of each color DNA than they pass on to their own children, so different children receive different pieces of their parents’ DNA, and varying percentages of their grandparents’ DNA.

I wrote about a 4 Generation Inheritance Study, here.

Perspective

Keep in mind that you will only inherit half of the DNA that each of your parents carries.

Looking at a chromosome browser, you match your parents on all of YOUR chromosomes.

Inheritance parental autosomal

For example, this is me compared to my father. I match my father on either his mother’s side, or his father’s side, on every single location on MY chromosomes. But I don’t match ALL of my father’s DNA, because I only received half of what he has.

From your parents’ perspective, you only have half of their DNA.

Let’s look at an illustration.

Inheritance mom dad

Here is an example of one of your father’s pairs of chromosomes 1-22. It doesn’t matter which chromosome, the concepts are the same.

He inherited the blue chromosome from his father and the pink chromosome from his mother.

Your father contributed half of his DNA to you, but that half is comprised of part of his father’s chromosome, and part of his mother’s chromosome, randomly selected in chunks referred to as segments.

Inheritance mom dad segments

Your father’s chromosomes are shown in the upper portion of the graphic, and your chromosome that you inherited from you father is shown below.

On your copy of your father’s chromosome, I’ve darkened the dark blue and dark pink segments that you inherited from him. You did not receive the light blue and light pink segments. Those segments of DNA are lost to your line, but one of your siblings might have inherited some of those pieces.

Inheritance mom dad both segments

Now, I’ve added the DNA that you inherited from your Mom into the mixture. You can see that you inherited the dark green from your Mom’s father and the dark peach from your Mom’s mother.

Inheritance grandparents dna

These colored segments reflect the DNA that you inherited from your 4 grandparents on this chromosome.

I often see questions from people wondering how they match someone from their mother’s side and someone else from their father’s side – on the same segment.

Understanding that you have a copy of the same chromosome from your mother and one from your father clearly shows how this happens.

Inheritance match 1 2

You carry a chromosome from each parent, so you will match different people on the same segment. One match is to the chromosome copy from Mom, and one match is to Dad’s DNA.

Inheritance 4 gen

Here is the full 4 generation inheritance showing Match 1 matching a segment from your Dad’s father and Match 2 matching a segment from your Mom’s father.

Your Parents Will Have More Matches Than You Do

From your parents’ perspective, you will only match (roughly) half of the DNA with other people that they will match. On your Dad’s side, on segment 1, you won’t match anyone pink because you didn’t inherit your paternal grandmother’s copy of segment 1, nor did you inherit your maternal grandmother’s segment 1 either. However, your parents will each have matches on those segments of DNA that you didn’t inherit from them.

From your perspective, one or the other of your parents will match ALL of the people you match – just like we see in Match 1 and Match 2.

Matching you plus either of your parents, on the same segment, is exactly how we determine whether a match is valid, meaning identical by descent, or invalid, meaning identical by chance. I wrote about that in the article, Concepts: Identical by…Descent, State, Population and Chance.

Inheritance on chromosomes 1-22 works in this fashion. So does the X chromosome, fundamentally, but the X chromosome has a unique inheritance pattern.

X Chromosome

The X chromosome is inherited differently for males as compared to females. This is because the 23rd pair of chromosomes determines a child’s sex.

If the child is a female, the child inherits an X from both parents. Inheritance works the same way as chromosomes 1-22, conceptually, but the inheritance path on her father’s side is different.

If the child is a male, the father contributes a Y chromosome, but no X, so the only X chromosome a male has is his mother’s X chromosome.

Males inherit X chromosomes differently than females, so a valid X match can only descend from certain ancestors on your tree.

inheritance x fan

This is my fan chart showing the X chromosome inheritance path, generated by using Charting Companion. My father’s paternal side of his chart is entirely blank – because he only received his X chromosome from his mother.

You’ll notice that the X chromosome can only descend from any male though his mother – the effect being a sort of checkerboard inheritance pattern. Only the pink and blue people potentially contributed all or portions of X chromosomes to me.

This can actually be very useful for genealogy, because several potential ancestors are immediately eliminated. I cannot have any X chromosome segment from the white boxes with no color.

The X Chromsome in Action

Here’s an X example of how inheritance works.

Inheritance X

The son inherits his entire X chromosome from his mother. She may give him all of her father’s or mother’s X, or parts of both. It’s not uncommon to find an entire X chromosome inherited. The son inherits no X from his father, because he inherits the Y chromosome instead.

Inheritance X daughter

The daughter inherits her father’s X chromosome, which is the identical X chromosome that her father inherited from his mother. The father doesn’t have any other X to contribute to his daughter, so like her father, she inherits no portion of an X chromosome from her paternal grandfather.

The daughter also received segments of her mother’s X that her mother inherited maternally and paternally. As with the son, the daughter can receive an entire X chromosome from either her maternal grandmother or maternal grandfather.

This next illustration ONLY pertains to chromosome 23, the X and Y chromosomes.

Inheritance x y

You can see in this combined graphic that the Y is only inherited by sons from one direct line, and the father’s X is only inherited by his daughter.

X chromosome results are included with autosomal results at both Family Tree DNA and 23andMe, but are not provided at MyHeritage. Ancestry, unfortunately, does not provide segment information of any kind, for the X or chromosomes 1-22. You can, however, transfer the DNA files to Family Tree DNA where you can view your X matches.

Note that X matches need to be larger than regular autosomal matches to be equally as useful due to lower SNP density. I use 10-15 cM as a minimum threshold for consideration, equivalent to about 7 cM for autosomal matches. In other words, roughly double the rule of thumb for segment size matching validity.

Autosomal Education

My blog is full of autosomal educational articles and is fully keyword searchable, but here are two introductory articles that include information from the four major vendors:

When to Purchase Autosomal DNA Tests

Literally, anytime you want to work on genealogy to connect with cousins, prove ancestors or break through brick walls.

  • Purchase tests for yourself and your siblings if both parents aren’t living
  • Purchase tests for both parents
  • Purchase tests for all grandparents
  • Purchase tests for siblings of your parents or your grandparents – they have DNA your parents (and you) didn’t inherit
  • Test all older generation family members
  • If the family member is deceased, test their offspring
  • Purchase tests for estimates of your ethnicity or ancestral origins

Y DNA

Y DNA is only inherited by males from males. The Y chromosome is what makes a male, male. Men inherit the Y chromosome intact from their father, with no contribution from the mother or any female, which is why men’s Y DNA matches that of their father and is not diluted in each generation.

Inheritance y mtdna

If there are no adoptions in the line, known or otherwise, the Y DNA will match men from the same Y DNA line with only small differences for many generations. Eventually, small changes known as mutations accrue. After many accumulated mutations taking several hundred years, men no longer match on special markers called Short Tandem Repeats (STR). STR markers generally match within the past 500-800 years, but further back in time, they accrue too many mutations to be considered a genealogical-era match.

Family Tree DNA sells this test in 67 and 111 marker panels, along with a product called the Big Y-700.

The Big Y-700 is the best-of-class of Y DNA tests and includes at least 700 STR markers along with SNPs which are also useful genealogically plus reach further back in time to create a more complete picture.

The Big Y-700 test scans the entire useful portion of the Y chromosome, about 15 million base pairs, as compared to 67 or 111 STR locations.

67 and 111 Marker Panel Customers Receive:

  • STR marker matches
  • Haplogroup estimate
  • Ancestral Origins
  • Matches Map showing locations of the earliest known ancestors of matches
  • Haplogroup Origins
  • Migration Maps
  • STR marker results
  • Haplotree and SNPs
  • SNP map

Y, mitochondrial and autosomal DNA customers all receive options for Advanced Matching.

Big Y-700 customers receive, in addition to the above:

  • All of the SNP markers in the known phylotree shown publicly, here
  • A refined, definitive haplogroup
  • Their place on the Block Tree, along with their matches
  • New or unknown private SNPs that might lead to a new haplogroup, or genetic clan, assignment
  • 700+ STR markers
  • Matching on both the STR markers and SNP markers, separately

Y DNA Education

I wrote several articles about understanding and using Y DNA:

When to Purchase Y DNA Tests

The Y DNA test is for males who wish to learn more about their paternal line and match against other men to determine or verify their genealogical lineage.

Women cannot test directly, but they can purchase the Y DNA test for men such as fathers, brothers, and uncles.

If you are purchasing for someone else, I recommend purchasing the Big Y-700 initially.

Why purchase the Big Y-700, when you can purchase a lower level test for less money? Because if you ever want to upgrade, and you likely will, you have to contact the tester and obtain their permission to upgrade their test. They may be ill, disinterested, or deceased, and you may not be able to upgrade their test at that time, so strike while the iron is hot.

The Big Y-700 provides testers, by far, the most Y DNA data to work (and fish) with.

Mitochondrial DNA

Inheritance mito

Mitochondrial DNA is passed from mothers to both sexes of their children, but only females pass it on.

In your tree, you and your siblings all inherit your mother’s mitochondrial DNA. She inherited it from her mother, and your grandmother from her mother, and so forth.

Mitochondrial DNA testers at FamilyTreeDNA receive:

  • A definitive haplogroup, thought of as a genetic clan
  • Matching
  • Matches Map showing locations of the earliest know ancestors of matches
  • Personalized mtDNA Journey video
  • Mutations
  • Haplogroup origins
  • Ancestral origins
  • Migration maps
  • Advanced matching

Of course, Y, mitochondrial and autosomal DNA testers can join various projects.

Mitochondrial DNA Education

I created a Mitochondrial DNA page with a comprehensive list of educational articles and resources.

When to Purchase Mitochondrial DNA Tests

Mitochondrial DNA can be valuable in terms of matching as well as breaking down brick walls for women ancestors with no surnames. You can also use targeted testing to prove, or disprove, relationship theories.

Furthermore, your mitochondrial DNA haplogroup, like Y DNA haplogroups, provides information about where your ancestors came from by identifying the part of the world where they have the most matches.

You’ll want to purchase the mtFull sequence test provided by Family Tree DNA. Earlier tests, such as the mtPlus, can be upgraded. The full sequence test tests all 16,569 locations on the mitochondria and provides testers with the highest level matching as well as their most refined haplogroup.

The full sequence test is only sold by Family Tree DNA and provides matching along with various tools. You’ll also be contributing to science by building the mitochondrial haplotree of womankind through the Million Mito Project.

Combined Resources for Genealogists

You may need to reach out to family members to obtain Y and mitochondrial DNA for your various genealogical lines.

For example, the daughter in the tree below, a genealogist, can personally take an autosomal test along with a mitochondrial test for her matrilineal line, but she cannot test for Y DNA, nor can she obtain her paternal grandmother’s mitochondrial DNA directly by testing herself.

Hearts represent mitochondrial DNA, and stars, Y DNA.

Inheritance combined

However, our genealogist’s brother, father or grandfather can test for her father’s (blue star) Y DNA.

Her father or any of his siblings can test for her paternal grandmother’s (hot pink heart) mitochondrial DNA, which provides information not available from any other tester in this tree, except for the paternal grandmother herself.

Our genealogist’s paternal grandfather, and his siblings, can test for his mother’s (yellow heart) mitochondrial DNA.

Our genealogist’s maternal grandfather can test for his (green star) Y DNA and (red heart) mitochondrial DNA.

And of course, it goes without saying that every single generation upstream of the daughter, our genealogist, should all take autosomal DNA tests.

So, with several candidates, who can and should test for what?

Person Y DNA Mitochondrial Autosomal
Daughter No Y – can’t test Yes, her pink mother’s Yes – Test
Son Yes – blue Y Yes, his pink mother’s Yes – Test
Father Yes – blue Y Yes – his magenta mother’s Yes – Test
Paternal Grandfather Yes – blue Y – Best to Test Yes, his yellow mother’s – Test Yes – Test
Mother No Y – can’t test Yes, her pink mother’s Yes – Test
Maternal Grandmother No Y – can’t test Yes, her pink mother’s – Best to Test Yes – Test
Maternal Grandfather Yes – green Y – Test Yes, his red mother’s – Test Yes – Test

The best person/people to test for each of the various lines and types of DNA is shown bolded above…assuming that all people are living. Of course, if they aren’t, then test anyone else in the tree who carries that particular DNA – and don’t forget to consider aunts and uncles, or their children, as candidates.

If one person takes the Y and/or mitochondrial DNA test to represent a specific line, you don’t need another person to take the same test for that line. The only possible exception would be to confirm a specific Y DNA result matches a lineage as expected.

Looking at our three-generation example, you’ll be able to obtain a total of two Y DNA lines, three mitochondrial DNA lines, and 8 autosomal results, helping you to understand and piece together your family line.

You might ask, given that the parents and grandparents have all autosomally tested in this example, if our genealogist really needs to test her brother, and the answer is probably not – at least not today.

However, in cases like this, I do test the sibling, simply because I can learn and it may encourage their interest or preserve their DNA for their children who might someday be interested. We also don’t know what kind of advances the future holds.

If the parents aren’t both available, then you’ll want to test as many of your (and their) siblings as possible to attempt to recover as much of the parents’ DNA, (and matches) as possible.

Your family members’ DNA is just as valuable to your research as your own.

Increase Your Odds

Don’t let any of your inherited DNA go unused.

You can increase your odds of having autosomal matches by making sure you are in all 4 major vendor databases.

Both FamilyTreeDNA and MyHeritage accept transfers from 23andMe and Ancestry, who don’t accept transfers. Transferring and matching is free, and their unlock fees, $19 at FamilyTreeDNA, and $29 at MyHeritage, respectively, to unlock their advanced tools are both less expensive than retesting.

You’ll find easy-to-follow step-by-step transfer instructions to and from the vendors in the article DNA File Upload-Download and Transfer Instructions to and from DNA Testing Companies.

Order

You can order any of the tests mentioned above by clicking on these links:

Autosomal:

Transfers

_____________________________________________________________

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

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:

______________________________________________________________

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

DNAPainter Instructions and Resources

DNAPainter garden

DNAPainter is one of my favorite tools because DNAPainter, just as its name implies, facilitates users painting their matches’ segments on their various chromosomes. It’s genetic art and your ancestors provide the paint!

People use DNAPainter in different ways for various purposes. I utilize DNAPainter to paint matches with whom I’ve identified a common ancestor and therefore know the historical “identity” of the ancestors who contributed that segment.

Those colors in the graphic above are segments identified to different ancestors through DNA matching.

DNAPainter includes:

  • The ability to paint or map your chromosomes with your matching segments as well as your ethnicity segments
  • The ability to upload or create trees and mark individuals you’ve confirmed as your genetic ancestors
  • A number of tools including the Shared cM Tool to show ranges of relationships based on your match level and WATO (what are the odds) tool to statistically predict or estimate various positions in a family based on relationships to other known family members

A Repository

I’ve created this article as a quick-reference instructional repository for the articles I’ve written about DNAPainter. As I write more articles, I’ll add them here as well.

  • The Chromosome Sudoku article introduced DNAPainter and how to use the tool. This is a step-by-step guide for beginners.

DNA Painter – Chromosome Sudoku for Genetic Genealogy Addicts

  • Where do you find those matches to paint? At the vendors such as Family Tree DNA, MyHeritage, 23andMe and GedMatch, of course. The Mining Vendor Matches article explains how.

DNAPainter – Mining Vendor Matches to Paint Your Chromosomes

  • Touring the Chromosome Garden explains how to interpret the results of DNAPainter, and how automatic triangulation just “happens” as you paint. I also discuss ethnicity painting and how to handle questionable ancestors.

DNA Painter – Touring the Chromosome Garden

  • You can prove or disprove a half-sibling relationship using DNAPainter – for you and also for other people in your tree.

Proving or Disproving a Half Sibling Relationship Using DNAPainter

  • Not long after Dana Leeds introduced The Leeds Method of clustering matches into 4 groups representing your 4 grandparents, I adapted her method to DNAPainter.

DNAPainter: Painting the Leeds Method Matches

  • Ethnicity painting is a wonderful tool to help identify Native American or minority ancestry segments by utilizing your estimated ethnicity segments. Minority in this context means minority to you.

Native American and Minority Ancestors Identified Using DNAPainter Plus Ethnicity Segments

  • Creating a tree or uploading a GEDCOM file provides you with Ancestral Trees where you can indicate which people in your tree are genetically confirmed as your ancestors.

DNAPainter: Ancestral Trees

  • Of course, the key to DNA painting is to have as many matches and segments as possible identified to specific ancestors. In order to do that, you need to have your DNA working for you at as many vendors as possible that provide you with matching and a chromosome browser. Ancestry does not have a browser or provide specific paintable segment information, but the other major vendors do, and you can transfer Ancestry results elsewhere.

DNAPainter: Painting “Bucketed” Family Tree DNA Maternal and Paternal Family Finder Matches in One Fell Swoop

  • Family Tree DNA offers the wonderful feature of assigning your matches to either a maternal or paternal bucket if you connect 4th cousins or closer on your tree. Until now, there was no way to paint that information at DNAPainter en masse, only manually one at a time. DNAPainter’s new tool facilitates a mass painting of phased, parentally bucketed matches to the appropriate chromosome – meaning that triangulation groups are automatically formed!

Triangulation in Action at DNAPainter

  • DNAPainter provides the ability to triangulate “automatically” when you paint your segments as long as you know which side, maternal or paternal, the match originates. Looking at the common ancestors of your matches on a specific segments tracks that segment back in time to its origins. Painting matches from all vendors who provide segment information facilitates once single repository for walking your DNA information back in time.

DNA Transfers

Some vendors don’t require you to test at their company and allow transfers into their systems from other vendors. Those vendors do charge a small fee to unlock their advanced features, but not as much as testing there.

Ancestry and 23andMe DO NOT allow transfers of DNA from other vendors INTO their systems, but they do allow you to download your raw DNA file to transfer TO other vendors.

Family Tree DNA, MyHeritage and GedMatch all 3 accept files uploaded FROM other vendors. Family Tree DNA and MyHeritage also allow you to download your raw data file to transfer TO other vendors.

These articles provide step-by-step instructions how to download your results from the various vendors and how to upload to that vendor, when possible.

Here are some suggestions about DNA testing and a transfer strategy:

Paint and 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

800 Articles Strong

800-strong

Today is something of a red-letter day. This is the 801st article published on this blog.

This blog, DNA-Explained, was christened on July 11, 2012 and will soon be 5 years old, as hard as that is to believe. In some ways, it feels like this blog has been around “forever” and in other ways, it feels like it’s very new, because there is always some interesting topic to write about.

Truthfully, I can’t believe I’ve written 800 articles. No wonder some of the letters are worn off of my keyboard. And it’s my second keyboard!

My original goal was one article per week, which would have been about 235 articles by now. I wasn’t sure I could accomplish that. It’s amazing what inspiration can do! I love genetic genealogy every bit as much today as I did then, if not more. What an incredibly exciting time to be alive with an unbelievable opportunity to participate in an unfolding field with new discoveries being made on an almost daily basis.

I had been considering a DNA blog when Spencer Wells, then Scientist in Residence at the National Geographic Society, suggested that I SHOULD author a blog. That encouragement was all it took to motivate me. Thanks so much Spencer for that final nudge!!!

spencer and me

Just 12 days after DNA-Explained’s launch, the Genographic 2.0 product was introduced and I was privileged to participate in that announcement.

I started writing articles in self-defense, truthfully, because I was receiving the same questions over and over again. I figured if I could write the answer once, I could then just point the next person with that same question to an answer that included graphics and illustrations and was a much better answer than I could provide in an e-mail.

Plus, repetitively recreating the same answer was a time-waster – and blogging to share publicly with the goal of helping lots of people learn seemed the perfect solution.

I had no idea, and I mean none, that DNA testing in the direct to consumer marketplace would explode like it has. I’m glad I started writing when I did, because there are ever-more people asking questions. That’s a good thing, because it means people are testing and learning what messages their DNA has for them.

Our DNA is the most personal record of our ancestors that we’ll ever have – and today more and more tools exist to interpret what those ancestors are telling us. We are still panning for gold on the frontier of science although we know infinitely more than we did a decade or 5 years ago, and we know less than we will 5 or 10 years from now. We are still learning every single day. That’s what makes this field so exciting, and infinitely personal.

Here’s part of what I said in my introductory article:

Genetic genealogy is a world full of promise, but it changes rapidly and can be confusing. People need to understand how to use the numerous tools available to us to unravel our ancestral history.

People also love to share stories. We become inspired by the successes of others, and ideas are often forthcoming that we would not have otherwise thought of.

In light of that, I’ve tried to include a wide variety of articles at every level so that there is something for everyone. I hope I’ve managed to make genetics interesting and shared some of my enthusiasm with you over the years.

In Celebration

To celebrate this 800 article-versary, I’m going to share a few things.

  • Article organization and how to find what you want
  • The 10 most popular articles of those 800
  • Two things people can do to help themselves
  • Articles I wish people would read
  • Questions asked most frequently

Then, I’m going to ask you what you’d like for me to write about in the future.

Articles Organization aka How To Find What You Want

Blogs allow you to group articles by both categories and tags, two ways of organizing your articles so that people and search engines can find them.

Each article is identified by categories. You can click on any of the categories, below, to see which articles fall into that category. These are also some of the keywords for the blog search feature.

I’ve also grouped articles by tags as shown on the sidebar of the blog. The larger text indicates tags with more articles.

800-tags

You can click on any of those as well (on the actual blog page) to view all the articles that fall into that tag group.

For example, one of my 52 Ancestor Stories would be tagged with “52 Weeks of Ancestors” but if it discussed Y DNA, that would be one of the categories selected.

At the end of every blog article, you can see the category or categories the article is posted under, tags and other pertinent information about that article.

800-end-of-article

The Top 10 Articles

  1. Proving Native American Ancestry Using DNA
  2. 4 Kinds of DNA for Genetic Genealogy
  3. Ethnicity Results – True or Not?
  4. Mythbusting – Women, Fathers and DNA
  5. Genealogy and Ethnicity DNA Testing – 3 Legitimate Companies
  6. How Much Indian Do I Have in Me???
  7. What is a Haplogroup?
  8. Thick Hair, Small Boobs, Shovel Shaped Teeth and More
  9. Ethnicity Testing and Results
  10. 23andMe, Ancestry and Selling Your DNA Information

The Two Things People Can Do To Help Themselves

  1. Search first.

Before asking a question, I wish people would try searching my blog for the answer. Using the search box in the upper right hand corner, the blog is fully key word searchable.

800-search

Furthermore, even if you can’t figure out the right key word to search, you can also find articles on my blog by searching for phrases using google.

2. Upload GEDCOM files.

Your DNA testing is only as good as the comparisons you can make, and the ancestors and ancestral links you can find. Please, please, PLEASE upload GEDCOM files to Family Tree DNA and GedMatch. If you don’t have a tree, you can create one at Family Tree DNA. Link your tree to your DNA results on Ancestry and share your results. 23andMe has no tree ability at this time.

The Articles I Wish People Would Read

In addition to some of the articles already listed in the top 10, I wish people would read:

Questions Asked Most Frequently

  • Questions relating to Native American heritage and testing.
  • Questions relating to ethnicity, especially when the results are unexpected or don’t seem to align with what is known or family oral history.
  • Overwhelmed newbies who receive results and don’t have any idea how to interpret what they’ve received, which is why I created the Help page.

The Future – What Articles Would You Like to See?

It’s your turn.

What topics would you like to see me cover in upcoming articles? Is there something in particular that you find confusing, or enticing, or exciting?

I’m not promising that I’ll write about every topic, and some may be combined, but articles are often prompted by questions and suggestions from readers.

And speaking of readers…

Thank You

A very big thank you to all of my subscribers and followers for making DNA-Explained so popular and such a success. You folks are amazing, infinitely giving and helpful. We really are a community!

thank-you

______________________________________________________________

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

 

Concepts – How Your Autosomal DNA Identifies Your Ancestors

Welcome to the concepts articles. This series presents the concepts of genetic genealogy, not the details.  I have written a lot of detailed articles, and I’ve linked to them for those of you who want more.  My suggestion would be to read this article once, entirely, all the way through to understand the concepts with continuity of thought, then go back and reread and click through to other articles if you are interested.

All of autosomal genetic genealogy is based on these concepts of inheritance and matching, so if you don’t understand these, you won’t understand your matches, how they work, why, or how to interpret what they do or don’t tell you.

The Question 

Someone sent me this question about autosomal DNA matching.

“I do not quite understand how the profiles can be identified to an ancestor since that person is not among us to provide DNA material for “testing” and “comparison.”

That’s a really good question, so let’s take a shot at answering this question conceptually.

Do you have a cat or dog?

Chica Pixie Quilt

I bet I could tell if I could see your clothes, your house, your car or your quilt. Why or how?  Because pets shed, and try as you might, it’s almost impossible to get rid of the evidence.  I went to the dentist once and he looked at my sweatshirt and said, “German Shepherd?” I laughed.

When your ancestor had children, he or she shed their DNA, half of it, and it’s still being passed down to their descendants today, at least for the next several generations. Let’s look, conceptually, at how and why this works.

In the following diagram, on the left you can see the generations and the relationships of the people both to the ancestor and to each other.

Our ancestor, John Doe, married a wife, J, and had 2 children. Gender of the children, in this example, does not matter.

Everyone receives one strand of DNA from their mother and one from their father. If you’re interested in more detail about how this works, click here.

In our example below, I’ve divided this portion of John’s DNA into 10 buckets. Think of each of these buckets as having maybe 100 units of John’s DNA.  You can think of pebbles in the bucket if you’d like.  Our DNA is passed, often, in buckets where the group of pebbles sticks together, at least for a while.  Since this is conceptual, our buckets are being passed intact from generation to generation.

John’s mother’s strand of DNA has her buckets labeled MATERNALAB and I’ve colored them pink to make them easy to identify. John’s father’s strand of DNA has his buckets labeled FATHERSIDE and is blue.  Important note – buckets don’t come colored coded pink or blue in nature – you have no idea which side your DNA comes from.  Yes, I know, that’s a cruel joke of Nature.

John married J, call her Jean. Jean also has 2 strands of DNA, one from her mother and one from her father, but in order to simplify things, rather than have two colors for the wives, I’d rather you think of this generationally, so the wives in each generation only have one color. That way you can see the wives’ DNA mixing with the husbands by just looking at the colors. Jean’s color is lavender.

DNA “Shedding” to Descendants

So, now let’s look at how John “sheds” his DNA to his two children and their descendants – and why that matters to us several generations later.

Concept ancestor inheritance

Please note that you can click on any of the graphics to make them larger.

In the examples above, the DNA that is descended in each generational line from John is bolded within the colored square. I also intentionally put it at the beginning and ends of the segments for each child so it’s easy to see.

In the first generation, John’s children each receive one strand of DNA from their mother, J, and one from John. John’s DNA that his children receive is mixed between John’s father’s DNA and John’s mother’s DNA – roughly 50-50 – but not exactly.

At every position, or bucket, during recombination, John’s child will receive either the value in John’s Mom’s bucket or the value at that location in John’s Dad’s bucket.  In other words, the two strands of John’s parent’s DNA, in John, combine to make one strand to give to one of John’s children.  Each time this happens, for each child conceived, the recombination happens differently.

Concept Ancestor inheritance John

In this case, John’s children will receive either the M or the F in bucket one.  In buckets 2 and 3, the values are the same.  This happens in DNA.  The child’s bucket 4 will receive either an E or H.  Bucket 5 an R or E.  Bucket 6 an N or R.  And so forth.  This is how recombination works, and it’s called “random recombination” meaning that we have not been able to discern why or how the values for each location are chosen.

Is recombination really random, like a coin flip?  No, it’s not.  How do we know?  Because clumps of neighboring DNA stick often together, in buckets – in fact we call them “sticky segments.”  Groups of buckets stick together too, sometimes for many generations.  So it’s not entirely random, but we don’t know why.

What we do know for absolutely positively sure is that every person get’s exactly half of their parents’ DNA on chromosomes 1-22.  We are not talking about the X chromosome (meaning chromosome 23) or mitochondrial DNA or Y DNA.  Different topics entirely relative to inheritance.

You can see which buckets received which of John’s parents’ DNA based on the pink and blue color coding and the letters in the buckets.  Jean’s contribution to Child 1 and Child 2 would be mixed between her parents’ DNA too.

Concept Ancestor inheritance child

In the first generation, Child 1 received 6 pink buckets (segments) from John’s mother and 4 blue buckets from John’s father – MATHERSLAB.  Child 2 received 6 blue buckets from John’s father and 4 pink buckets from John’s mother – FATHERALAB.  On the average, each child received half of their grandparents’ DNA, but in reality, neither child received exactly half.

Note that Child 1 and 2 did not necessarily receive the SAME buckets, or segments, from John’s parents, although Child 1 and 2 did receive some buckets with the same letters in them – ATHERLAB.

If you’re thinking, “lies, damned lies and statistics” right about now, and chuckling, or maybe crying, join the club!

Looking at the next generation, John’s Child 1 married K and John’s Child 2 married O.

Child 1

Let’s follow John’s pink and blue DNA in Child 1’s descendants.  Child 1 marries K and had one child.

Concept Ancestor inheritance grandchild child 1 c

John’s grandchild by Child 1 has one strand of DNA from Child 1’s spouse K and one strand from Child 1 which reads MATJJJJLAB. You can see this by K’s entire strand and the grandchild’s other strand, contributed by Child 1, being a mixture of John’s DNA along with his wife J’s DNA.  In this case, for these buckets, John’s mother’s pink DNA is only being passed on.  John’s father’s buckets 4-7 were “washed out” in this generation and the grandchild received grandmother J’s DNA instead.

Concept Ancestor inheritance gen 4 c

In the next generation, 3, John’s grandchild married P and had generation 4, the great-grandchild. Generation 4 of course carries a strand from wife P, but the Doe strand now carries less of John’s original DNA – just MA and LAB at the beginning and end of the grouping.

Concept Ancestor inheritance gen 5 c

In the next generation, 5, the great-great-grandchild, you can see that now John Doe’s inherited DNA is reduced to only the AB at the right end.

Concept Ancestor inheritance gen 6

In the next generation, 6, the great-great-great-grandchild carries only the A, and in the final generation, below, the great-great-great-great-grandchild, none of John Doe’s DNA is carried by that descendant in those particular buckets.

Concept Ancestor inheritance gen 7 c1

Can there be exceptions? Yes.  Buckets are sometimes split and the X chromosome functions differently in male and female inheritance.  But this example is conceptual, remember.

You always receive exactly half of your parents’ DNA, but after that, how much you receive of an ancestor’s DNA isn’t 50% in each generation. You saw that in our examples where both Child 1 and Child 2 inherited a little more or a little less than 50% of each of John’s parents’ DNA.

Sometimes groups of DNA buckets are passed together and sometimes, the entire bucket or group of buckets are replaced by DNA from “the next generation.”

To summarize for Child 1, from John Doe to generation 7, each generation inherited the following buckets from John, with the final generation, 7, having none of John’s DNA at all – at least not in these buckets.

concept child 1

Now, let’s see how the DNA of Child 2 stacks up.

Child 2

You can follow the same sequence with Child 2. In the first generation, Child 2 has one strand of John’s DNA and one of their mother’s, J.

Child 2 marries O, Olive, and their child has one strand from O, and one from Child 2.

Concept Ancestor inheritance gen 3 c 2

Child 2’s contributed strand is comprised of DNA from John Doe and mother J.  You can see that the grandchild has FA and ALAB from John, but the rest is from mother J.

Concept Ancestor inheritance gen 4 c 2

The grandchild (above) married Q and their child generation 4, inherits most of John’s DNA, but did drop the A .

Concept Ancestor inheritance gen 5 c 2

Sometimes the DNA between generations is passed on without recombining or dividing.  That’s what happened in generation 5, above, and 6 below, with John’s DNA.

Concept Ancestor inheritance gen 6 c 2

Generations, 5 (great-great-grandchild) and 6 (great-great-great-grandchild) both receive John’s F and AB, above.

Concept Ancestor inheritance gen 7 c 2

However, in the 7th generation, the great-great-great-great-grandchild only inherits John’s bucket with B.  The F and A were both lost in this generation.

concept child 2

This summary of the inheritance of John’s DNA in Child 2’s descendants shows that in the 7th generation, that individual carries only one of John’s DNA buckets, the rest having been replaced by the DNA of other ancestors during the inheritance recombination process in each generation.

Half the Equation

To answer the question of how we can identify the profile of a person long dead is not answered by this inheritance diagram, at least not directly – because we don’t KNOW how much of John’s DNA we inherited, or which parts.  In fact, that’s what we’re trying to figure out – but first, we had to understand how we inherited DNA from John (or not).

Matching with known family members is what actually identifies John’s DNA and tells us which parts of our DNA, if any, come from John.

Generational Matching

Let’s say I’m in the first cousin generation and I’m comparing my autosomal DNA against my first cousin from this line.  First cousins share common grandparents.

Assuming that they are genetically my first cousin (meaning no adoptions or misattributed parentage,) they are close enough that we can both be expected to carry some of our common ancestor’s DNA. I wrote an in-depth article about first cousin matching here, but for our purposes, we know genetically that first cousins are going to match each other virtually 100% of the time.

Here’s a nice table from the Family Tree DNA Learning Center that tells us what to expect in terms of matching at different relationship levels.

concept generational match

The reason our autosomal DNA matches with our reasonably close relatives is because we share a common ancestor and have inherited at least a bucket, if not more than one bucket, of the same DNA from that ancestor.

That’s the ONLY WAY our DNA could match at the bucket level, given what we know about inheritance. The only way to get our DNA is through our parents who got their DNA through their parents and ancestors.  Now, could we share more than one common ancestral line?  Yes – but that’s beyond conceptual, for now.  And yes, there is identical by chance (IBC), which doesn’t apply to close relatives and in general, nor to larger buckets. If you want to read more about this complex subject, which is far beyond conceptual, click here.

Now, let’s see how we identify our ancestor’s DNA!

Concept ancestor matching

Let’s look at people of the same generation of descendants and see how they match each other.  In other words, now we’re going to read left to right across rows, to compare the descendants of child 1 and 2.  Previously, we were reading up and down columns where we tracked how DNA was inherited.

Bolded letters in buckets indicate buckets inherited from John, just like before, but buckets with black borders indicate buckets shared with a cousin from John’s other child.  In other words, a black border means the DNA of those two people match at that location.  Let’s look at the grandchildren of John compared to each other.  John’s grandchildren are first cousins to each other.

Concept ancestor matching 1c

Our first cousins match on 4 different buckets of John’s DNA: A, L, A and B.  In this case, you can see that both individuals inherited some DNA from John that they don’t share with each other, such as their first letters, M for Child 1 and F for child 2.  Because they inherited different pieces from John, because he inherited those pieces from different ancestors, the first cousins don’t match each other on that particular bucket because the letters in their individual buckets are different.

Yes, the first cousins also match on wife J’s DNA, but we’re just talking about John’s DNA here.  Now, let’s look at the next generation.

Concept ancestor matching 2c

Our second cousins, above, match on four buckets of John’s DNA.  Yes, the A bucket was inherited from John’s Mom in one case, and John’s Dad in the other case, but because the letter in the bucket is the same, when matching, we can’t tell them apart.  We only “know” which side they came from, in this case, because I told you and colored the buckets pink and blue to illustrate inheritance.  All the actual software matching comparison has to go by is the letter in the bucket.  Software doesn’t have the luxury of “knowing” because in nature there is no pink and blue color coding.

concept ancestor matching 3c

Our third cousins, above, match, but share only A and B, half as much of John’s DNA as the second cousins shared with each other.

Concept ancestor matching 4c

Our 4th cousins, above, are lucky and do match, although they share only one bucket, A, of John’s DNA, which happens to have come from John’s mother.

Concept ancestor matching 5c

By the time you get down to the 5th cousins, meaning the 7th generation, the cousins’ luck has run out, because these two 5th cousins don’t match on any of John’s DNA.

Most 5th cousins don’t match and few 6th cousins match, at least not at the default thresholds used by the testing companies – but some do.  Remember, we’re dealing with matching predictions based on averages, and actual individual DNA inheritance varies quite a bit.  Lies, damned lies and statistics again!

You can adjust your own thresholds at GedMatch, in essence making the buckets smaller, so increasing the odds that the contents of the buckets will match each other, but also increasing the chances that the matches will be by chance.  Again, beyond conceptual.

concept buckets inherited

While this is how matching worked for these comparisons of descendants, it will work differently for every pair of people who are compared against each other, because they will have, or not have, inherited different (or the same) buckets of DNA from their common ancestor.  That’s a long way of saying, “your mileage will vary.”  These are concepts and guidelines, not gospel.

Now, let’s put these guidelines to work.

Matching People at Testing Companies

Ok, so now let’s say that I match Sarah Doe. I don’t know Sarah, but we are predicted to be in the 2nd or 3rd cousin range, based on the amount of our DNA that we share.

As we know, based on our inheritance example, amounts of shared DNA can vary, but we may well be able to discern a common ancestor by looking at our pedigree charts.

Sure enough, given her surname as a hint, we determined that John Doe is our common ancestor.

That’s great evidence that this DNA was passed from John to both of us, but to prove it takes a third person matching us on the same segment, also with proven descent from John Doe. Why?  Because Sarah and I might also have a second common genealogical line, maybe even one we don’t know about, that’s isn’t on our pedigree chart. And yes, that happens far more than you’d think. To prove that Sarah Doe and my shared DNA is actually from John Doe or his wife, we need a third confirmed pedigree and DNA match on that same bucket.

A Circle is Not a Bucket

If you just said to yourself, “but Ancestry doesn’t show me buckets,” you’re right – and a Circle is not a bucketA Circle means you match someone’s DNA and have a common tree ancestor.  It doesn’t mean that you or any Circle members match each other on the same buckets. A bucket, or segment information, tells you if you match on common buckets, which buckets, and exactly where.  You could match all those people in a Circle on different buckets, from completely different ancestors, and there is no way to know without bucket information.  If you want to read more about the effects of lack of tools at Ancestry, click here and here.

Proof

Matching multiple people on the same buckets who descend from the same ancestor through different children is proof – and it’s the only proof except for very close relatives, like siblings, grandparents, first cousins, etc.  Circles are hints, good hints, but far, far from proof.  For buckets, you’ll need to transfer your Ancestry results to Family Tree DNA or to GedMatch, or preferably, both.

I’m most comfortable if at least two of the individuals of a minimum of three who match on the same buckets and share an ancestor, which is called a triangulation group, descend from at least two different children of John.  In other words, the first common ancestor of the matches is John and his wife, not their children.

Cross generational matches 2

The reason I like the different children aspect is because it removes the possibility that people are really matching on the downstream wives DNA, and not John’s.  In other words, if you have two people who match on the same buckets, A and B above, who both descend from John’s Child 1 who married K, they also will share K’s DNA in addition to John’s.  So their match to each other on a given bucket might be though K’s side and not through John’s line at all.

Let’s say A and B have a match to unknown person D who is adopted and doesn’t know their pedigree chart.  We can’t make the presumption that D’s match to A and B is through John Doe and Jean, because it might be through K.

However, a match on the same buckets to a third person, C, who descends through John’s other child, Child 2, assuming that Child 2 did not also marry into K’s (or any other common) line, assures that the shared DNA of A and B (and C) in that bucket is through John or his wife – and therefore D’s match to A, B and C on that bucket is also through the same common ancestor.

If you want to read more about triangulation, click here.

In Summary

The beauty of autosomal DNA is that we carry some readily measurable portion of each of our ancestors, at least the ones in the past several generations, in us. The way we identify that DNA and assign it to that ancestor is through matching to other people on the same segments (buckets) that also descend from the same ancestor or ancestral line, preferably through different children.  In many cases, after time, you’ll have a lot more than 3 people descended from that ancestral line matching on that same bucket.  Your triangulation group will grow to many – all connected by the umbilical lifethread of your common ancestors’ DNA.

As you can see, the concepts, taken one step at a time are pretty simple, but the layers of things that you need to think about can get complex quickly.

I’ll tell you though, this is the most interesting puzzle you’ll ever work on!  It’s just that there’s no picture on the box lid.  Instead, it’s incredible real-life journey to the frontiers inside of you to discover your ancestors and their history:)  Your ancestors are waiting for you, although my ancestors have a perverse sense of humor and we play hide and seek from time to time!

______________________________________________________________

Disclosure

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

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Services

Genealogy Research

The Concepts Series

clock

Sometimes we get caught up in the details of how DNA testing for genetic genealogy works and what it means. Then someone asks a simple conceptual question, and I have to step back and figure out how to not tell them how to build a clock, but simply answer the question of what time it is.

pocketwatch

Someone sent me this query about autosomal DNA matching.

“I do not quite understand how the profiles can be identified specially to an ancestor since that person is not among us to provide DNA material for “testing” and comparison.”

That used to be a common question, but less so now, or so I thought. But maybe it’s just because people aren’t asking anymore, or I’m talking to a different audience.

So, I’m introducing a “Concepts” series of articles. These articles won’t explain the specifics of “how to,” but will explain the concepts of genetic genealogy – just the concepts.  For details, how to and exceptions – and you know there are always exceptions, you can dig deeper.

If you have a basic concept question about genetic genealogy or know of one you’d like to see addressed, drop me a note or attach it as a comment to this article. I’ve discovered that many times concepts questions begin with a phrase like, “Maybe I’ve missed something, but…..”

I’ll be adding the Concepts articles here as I publish them.  And yes, the first article will be “How Your Autosomal DNA Identifies Your Ancestors.”

Concepts Articles

______________________________________________________________

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