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Help understanding genetic distance

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  • Help understanding genetic distance

    Hello There:

    I have the following case, I did a Y37 analysis, and joined a project with my surname, not so many people, we are only 13 people, but analyzing the matches one by one I found something interesting, there is a guy that has the following differences with me:

    on 12 markers, we differ by 2 in mark DYS390 (I'm 23, he's 25)
    on 25 markers, we differ by 1 in mark DYS448 (I'm 26, he's 25)
    on 37 markers, we differ by 1 in mark DYS576 (I'm 10, he's 11)
    on 37 markers, we differ by 1 in mark DYS438 (I'm 15, he's 16)

    So, this guy doesn't show as match of me in Y12,Y25,Y37

    Is this happens because on Y12 we have 2 Genetic distance?
    on Y25 because we have 3 (2 on Y12 + 1 on Y25) Genetic Distance?, and Y37 because we have 5 (2 on Y12 + 1 on Y25 + 2 in Y37)?.

    In this case I can't contact this guy, and there is not an admin on the project to write him in order to ask him any contact information or his help to get in touch with this person, and this guy has only Y37 analysis, so there is no way to advance and see if we still has a reasonable match on Y67.

    saludos and thanks in advance

  • #2
    there are limits in place as to what FTDNA considers a match. At each level that limit increases. For 12 it is GD of 1, 25 is 2 and 37 is 4. It would appear that this person is one GD too much away for each of the tests. There is a chance that he is closer at an increased testing level but you would have to upgrade to verify(assumes he is tested higher).

    Now having said all of that a GD of 5 at Y37 is several hundred years(or more) away from your MRCA.

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    • #3
      thanks for your reply

      Hello High734:

      I appreciate your comment, sadly He only has Y37 analysis, so I can't go beyond this YMark, I'm interested in this guy, because precisely I'm looking forward to have any information of two brothers of my GGGfather, that emigrated with him from Spain and never got in touch again, my GGGfather was born two hundred years ago in 1808. I know that there will be extremely lucky to find any male descendency of them in the web page, but who knows.

      saludos

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      • #4
        The common ancestor in the direct paternal line at GD of 5 at Y37 is much more likely to be from thousands of years ago rather than a few hundred years ago. Even at 67 markers a GD of 5 can be from thousands of years ago and is why either Y111 tests or BigY tests are needed for proof that the common is from hundreds and not thousands of years ago.

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        • #5
          Hi Armando

          Thanks Armando:

          So, what would be a proper Genetic Distance to consider a possible match at GGGfather relative level? I entirely ignore that information, is it possible to estimate it?.

          saludos and thanks in advance.

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          • #6
            Originally posted by paco7425 View Post
            Thanks Armando:

            So, what would be a proper Genetic Distance to consider a possible match at GGGfather relative level? I entirely ignore that information, is it possible to estimate it?.

            saludos and thanks in advance.
            Normally you want a GD of 3 or less at 37 markers and for that to stay basically the same at 67 and 111 markers.

            It's unfortunate that so few people out of the total population get Y-DNA testing at all and when they do many don't test to 67 markers. Y-DNA testing is even less popular with Hispanics than with people in the U.S. with British Isles ancestry.

            Saludos

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            • #7
              thanks for your reply

              thanks again Armando

              Now i'ts clear to me what Genetic Distance to seek, will wait and see what happens.

              saludos

              Comment


              • #8
                Interpreting the Big Y results turns out to be extremely complicated. Just from what you see on the Big Y results page, it is not possible to tell what SNP's you do or don't have, apart from those specifically listed. It is necessary to delve into the BAM file, and that is best left to someone with experience.

                By all means, join the appropriate surname and haplogroup projects! If you happen to belong to a haplogroup where someone is analyzing the BAM files in a systematic way, you may get the answer for free. If that is not the case, services such as YFull can help for a small fee (and once you join, you and others will continue to benefit from your data).

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