Triangulation for Y DNA

Based on the number of questions I’m receive about triangulation, it’s time to write an article.

There are two kinds of triangulation that we use in genetic genealogy.  One type is for the Y chromosome and it’s to determine the original values of the DNA of the common ancestor.  The second type of triangulation is for autosomal DNA and it’s to determine if you share a common ancestor with someone and what the DNA of that ancestor looked like.

This article is about the first type, for Y DNA.

Why would you want to use triangulation?

Sometimes in order to know if a particular line has descended from an ancestor, you need to know what that ancestor’s Y DNA marker values were.

For example, if you have an ancestor born in the 1600s, and he had two sons whose descendants tested today, each line could have 4 mutations each, or 6, which could put the matching software over the threshold – meaning they might not be reported as matches.  We have this situation in one of the Estes lines that seems to be particularly prone to mutate.

Family Tree DNA has set up match thresholds.  For someone to be listed as your match, they need to have no more than the following total number of mutations difference from your results.

Markers in Panel Tested Maximum Number of Mutations Allowed


0 unless in a common project, then 1









So you can see that if you have a high number of mutations in the first panel or two, you might not show as a match.

But if you know what the original ancestors Y-line DNA looks like, then it’s easy to tell that they really are matches and that both lines have simply had several mutations.

It’s much more accurate to compare everyone to the original ancestor instead of trying to compare them to each other.

Let’s take a look at the Estes project by way of example.

Abraham Estes, the progenitor of the Southern Estes line was born in 1647 in Nonington, Kent, England.  He immigrated to Virginia in 1683 and began begetting shortly thereafter.  His wife was Barbara, and although the internet is full of family trees that say her last name is Brock, there is not one shred of evidence to support that.  In any case, Abraham and Barbara had a total of 8 sons who lived and the sons had about 42 sons, so we have a good number of Estes families throughout the US today, mostly descending from Abraham.  There is also a northern line founded by Abraham’s cousin, Richard Estes although they don’t have nearly as many descendants.

triangulation Y dna

This chart shows the results of DNA testing through 7 different Estes lines, 6 of which are Abraham’s sons and one of which is a descendant of the Northern line.

The green row at the top is Abraham’s reconstructed DNA, and now, everyone in the project gets compared to Abraham on my spreadsheet.

It’s easy to see how this is done.  For each marker, beginning with 393, we determine what the normal value is for the family.  For marker 393, all lines carry a value of 13.  One line, John through Elisha, shows a mutation to a value of 14 which would signal a line marker mutation for this particular line.  This is quite useful, because when we see someone who carries a value of 14 at this location, especially in conjunction with any other line marker mutations that might exist in that line, like a value of 11 at marker 391, we know where to look genealogically to find the tester’s place in the family.  Line marker mutations are great guideposts.

So, marker by marker, I’ve reconstructed Abraham, shown at the top in green.

Marker Frequency

You might wonder why the value of 25 at 390 is red and underscored and 12 at 391 is bolded, red and underscored.

One of the things I do for each of my family lines, and for clients who order Personalized DNA Reports, is to determine which of their markers carry rare values.  In this case, the value of 25 at 390 is found in only 16% of haplogroup R1b1a2.  The value of 12 at 391 is found in only 4% of the haplogroup R1b1a2 population.  My threshold for rare markers is less than 25% and for very rare, 6% or less.  Bold red indicates very rare, red indicates rare and the underscore is present so that people printing in black and white can see the difference

Why and how does this make a difference?  In a situation where you’re trying to decide if someone really does match the Estes line, this information can be a big help.

The last kit on the chart does carry the Estes surname, but does not match the Estes line genetically.  This is obvious by looking at all the yellow squares, which are mismatches to Abraham, but let’s say that this person tested at 12 markers and he matched the Estes DNA on all of our rare markers, but mismatches a couple on the more common markers.  This is more likely a true Estes match than if they mismatch us on all of our rare markers.  The Estes rare markers combined create a type of family genetic fingerprint.  This is particularly important for adoptees.

And yes, to answer the next question, a Marker Frequency Table can be purchased separately for those who want their marker frequencies through 111 markers, but don’t want a Personalized DNA Report, by purchasing a Quick Consult.  A marker frequency table looks like this but extended, of course, through all of your markers:

Frequency table

Now, we know what the original Abraham Estes’s DNA looked like.  We also know which of our markers are unique.  This can also help us when comparing to other surnames we may be related to before the advent of surnames.  There is family history to be gleaned from those matches as well.

And lastly, because we also have cousin Richard’s DNA signature, we can use that information to reconstruct the common ancestor of Abraham Estes and Richard Estes, which is the grandfather of both men, Robert Estes, born 1555 in Ringwould, Kent, England.  Not bad for genetic technology, reaching back more than 450 years in time and telling us what our ancestor’s DNA looked like, and all without even reaching for a shovel.



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47 thoughts on “Triangulation for Y DNA

  1. Wow! What a great explanation. Thank you for sharing your knowledge with the rest of us. This explains a lot. So would you define Y-DNA triangulation as the comparing of descendants Y-DNA to determine the original values of the common ancestor’s Y-DNA? I find your explanation helpful because it shows how we can locate common relatives prior to when surnames became popular which, I’m told, was about 1,000 years ago.

    • Yes, that’s exactly right. When surnames were adopted depends on where your ancestor lived. About 1066 in England, 1711 in Holland and in some parts of the Jewish diaspora, not until in the 1800s.

  2. Thank you. You always make these post so easy for us to understand. It sure makes it easier to know how to put all our genetic information together to find our roots. I enjoy your posts.

  3. Now can you do an article on the autosomal DNA? I do not have anyone else in my family willing to test so I guess my AncestryDNA raw data will not be able to tell me much.

  4. DR…I’ll try not to send too much, but this article might help explain my confusion about our Father’s ydna steps…Glenn

    Sent from my iPad

  5. My husband matches all of Abraham’s markers but I can’t further back than a 1874 birth on his Estes line. Any suggestion of where to go from here or what type of consultation might be best?
    Are the seven Estes lines posted somewhere?

  6. Roberta, do you know of any other tool we can use for chromosome painting until GedMatch accepts data again? I just got back some results and I’m dying to play around with them !

    • Not really. Some of the submitters used to have versions on their own pages. After they were combined at GedMatch, I stopped using and tracking them individually. You’d have to poke around to see.

  7. I love reading your articles which have helped me move from dummy to idiot when it comes to DNA, many thanks.
    However i just received an email from the K Project on FTDNA and i am not sure i understand what they are talking about, can you explain.
    I have been asked to approve my sample for research and join the K Project which i have done, i just don’t know why.
    See Below-

    Let me explain your mutations from the top. The 1189C and 10398G mutations get you to K1. Your 146C, 152C and 498- get you into the major K1c subclade. K1c1 is defined by 9093G and 11377A, while K1c1b adds 15900C. You have two additional coding-region mutations that are unique to K1c1b. Both are found in several other haplogroups. Your 13651G is found independently in another K subclade, but its appearance in the neighboring K1c1d subclade may be an indication of some very distant connection between the two subclades. 15289C does not appear in any published K sequences or in Project sequences. Your other 6 HVR and 20 coding-region mutations are those which get all of us from the Cambridge Reference Sequence to K. K1c1b is about 2,500 years old and is found widely in mostly Northern Europe.

    • Joining projects helps you by being able to look at the maps and who you are grouped with and inferring history from that information. Allowing your sample to be used for research is how all of the haplogroups have been discovered, how the migration history is inferred, etc. Bill Hurst has worked closely with Dr. Doron Behar for several years now to redefine the mtdna haplogroup tree – so you might want to ask him his perspective on why as well. Here’s an article that might help.

  8. I’m very interested in how you used the rare allele marker frequencies to see specific lines. I’m a DNA project administrator and have wanted to understand this better. One question I had was that the chart gave frequencies for R1b but earlier in the text you mention R1b1a2. Whit Althey (and others) have published R1b frequencies but what about the R1b1a2 frequencies? Do you have a reference publication you could share or is this something that you have developed yourself? Thanks for your timely and as always educational posts.

    • I have developed an allele frequency table for all 111 markers for each major haplogroup. For awhile, I was also doing subgroups, but they really were not useful, or more useful, as compared to the major haplogroups. I use this table for each of my clients. There is no reference publication because I have done the work and maintain it myself as part of my business.

      • I too am a project administrator and am interested in the relationship between Y-DNA markers, Haplogroups, and subgroups. If you ever chose to publish such a work I’m sure all your income from such a wonderful tool would be hopelessly lost. Copyright laws would allow anyone to quote from such a resource without paying a royalty. Hopefully one day there will be some way for you to share what you learned that will be both financially beneficial to you and affordable to the masses. Are you or any researchers you know of working on the relationship between Y-DNA STRs and SNPs? As I understand it, STRs can only project a Haplogroup or subgroup where SNPs can confirm them. Is this because there’s not enough STR research to make them as certain as SNPs or because STRs aren’t as reliable in indicating the Haplogroup?

        • The past couple of years has been so interesting in STR and SNP-land. We’re now discovering what I would term “family SNPs” in some cases. Of course the only difference between a “family snp” and a full blown haplogroup subgroup is time and survival of paternal line descendants. The way we first knew to look for SNPs was unusual groupings of STRs that seemed to indicate a group.

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  10. Terminal STR question
    My haplogrp is R1b1a2 = R-M269. There are several matches at 37 level which are 1 step. TiP tool predicts a common ancestor at less than 12 generations with 95% confidence. One of this matches also tested for Teminal STR (shows an L23) . Here is my question: if I test and get a different Terminal STR does it mean that there is no such common ancestor and therefore the TiP prediction actually is invalid? Or in other words: does this further testing advance my primary goal to find ancestors relevant in the genealogical sense?

    • It depends. I know, that’s an awful answer. The problem is this. You know what the other person’s terminal SNP is listed as, but you don’t know if they tested further and were negative, or if they didn’t test further. So let’s say you both have a different terminal SNP, but it’s in the same SNP pedigree chart, and one is just upstream of the other. Based on this, you know two things. One, that does NOT exclude you from being from the same line and two, you need now to actually talk to the person and see what they were tested for. If they were NOT tested as far downstream as you, then they could carry the same terminal SNP as you. If they were tested on that SNP and were negative, at Family Tree DNA (not through Geno 2.0 – some probes didn’t work there), then you can surmise that you are in the same family line UNLESS it is a private family SNP.

      • Roberta, I’ve maintained personal websites for years and know how few comment when they have little to say but, “Thanks.” I think I perhaps speak for many (statistically speaking) when I say this reply above is EXACTLY the reason why your blog is so interesting. You break things down to the nuts and bolts. We need this! In behalf of the silent majority, “Thanks.”

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  13. Hi Roberta, Is there any way of using Y-DNA to label segments in the Autosomal DNA. I realize that they are two separate methods of testing. Just as 23andMe labels the X Chromosome and the segments that they match, I’m interested in labeling the Y chromosomes on the segments that they match. Right now at the Y-37 level, I have a 1 step match but that doesn’t insure me that we are really related, does it?

    In addition, I was reading your column about probes not working in the Geno 2.0 test but have also read some of your thoughts about Britain’s DNA. I realize that BritainsDna cannot be incorporated into the FTDNA but which one really gives me the most for the money invested and can be used most effectively. Would you take the oldest distant relative and have him test at one of these companies for the deep clade? Or would you take a younger more closely related male?

    In the effort to rebuild an ancestor’s Y-DNA, how many contributors does one really need to have in order to do this?

    Lastly, if a brick wall is reached already by 1880 on both sides of the paternal family, how does one begin to make this wall crumble by using DNA. It feels like when I track my matches back to what I know, I’m still not finding the common ancestor. One of your articles addresses the point about the estimates just being estimates and that sometimes the common ancestor is further back. When one uses triangulation for autosomal DNA at 23 and Me, some of the matches will match other matches but not on the same segments as mine, Are these matches matches of any significance for me when they occur on segments and chromosomes than where I match each person? Thanks for your response. I know this is decent number of questions but I appreciate your answer.

  14. Is there any way to use the Y-DNA to label the Paternal line in the Autosomal DNA or is this just two entirely separate tests that do not cross over. Just as the 23 and me shows the X Chromosome and the segments where they can be found, I would like to know if the same is possible for the Y-DNA.

    I’m interested in a deep clade test but am torn between National Geogrphic’s Geno 2.0 and the Britainsdna which I’ve heard can be interpreted and is now more advanced than the Geno 2.0. Which would you suggest and why? How much further testing will be necessary if I go the Geno 2.0 route.

    I read up above about rebuilding an ancestor’s Y-dna., How many contributors does one need to get an accurate picture. Is there a book to read that explains how to interpret raw data? If I don’t know my ancestors past 1880 and I don’t recognize my matches that are supposedly closer, is there anything thing you could suggest to narrow down the elusive ancestor? Thank you for your column. It has been very informative.

    • The Y and autosomal are two different tests. Regarding advanced Y testing – just hold tight for a bit. The landscape is changing rapidly. There may be new announcements at the conference at the end of this week.

      How many contributors you need depends on who you match and how the DNA was passed. I just read yesterday that one gentleman who has been working on this diligently for about 2 years now has about 80% of his DNA mapped to an ancestor. Just be persistent.

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  21. It seems like it would be logical for a mutation to be passed down to all of the sons and descendants in YDNA. Is that true? Thanks so much for all your work!!!

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