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Which is more important? Genetic distance or time to most recent common ancestor?

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  • Which is more important? Genetic distance or time to most recent common ancestor?

    I have a match with someone who isn't a match according to genetic distance, but all the mismatch markers are 3-4 times faster than the average for the 37 marker test, so the time to most recent common ancestor is actually more recent than for people who fall within the genetic distance maximum. Does this mean anything?

  • #2
    Do you have TiP result for you and your non-match? If you are both in a project, that project administrator can run TiP for you.

    Meaning? For example, you might get that you have 14% chance to be related in 8 generations, as opposed to 12% chance in 8 generations with the other people.

    Both of you might want to upgrade to at least Y-DNA67, and/or SNP testing.


    Mr W

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    • #3
      One thing you may want to consider is testing a different family member to rule out recent mutations in your line.

      For example testing a paternal Uncle or someone from your fathers paternal Cousins line that shares the same yDNA (surname)line

      My direct line (my Father and Grandfather) has had multiple recent mutations that give our line a GD of 4 at the 37 and 67 marker level to my Fathers paternal 1st cousin. My fathers 1st cousin is the closest to our surname matches with GD of 0 to 2 on those levels. My fathers (and his brother) results lose out on many of the matches that his cousin shows.
      Last edited by prairielad; 23 October 2016, 01:35 AM.

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      • #4
        Originally posted by prairielad View Post
        One thing you may want to consider is testing a different family member to rule out recent mutations in your line.

        For example testing a paternal Uncle or someone from your fathers paternal Cousins line that shares the same yDNA (surname)line

        My direct line (my Father and Grandfather) has had multiple recent mutations that give our line a GD of 4 at the 37 and 67 marker level to my Fathers paternal 1st cousin. My fathers 1st cousin is the closest to our surname matches with GD of 0 to 2 on those levels. My fathers (and his brother) results lose out on many of the matches that his cousin shows.
        That is very true.

        My close family has three different haplotypes. And reading the results right now, excluding ourselves, the haplotypes have at 12 markers:
        • 33 exact matches
        • 157 exact matches
        • 2617 exact matches


        Mr W

        P.S.
        We also did Family Finder and SNP tests, so common patrilineal genetic ancestry is confirmed.

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        • #5
          Originally posted by dna View Post
          Do you have TiP result for you and your non-match? If you are both in a project, that project administrator can run TiP for you.

          Meaning? For example, you might get that you have 14% chance to be related in 8 generations, as opposed to 12% chance in 8 generations with the other people.

          Both of you might want to upgrade to at least Y-DNA67, and/or SNP testing.


          Mr W
          Nobody can have a TiP for anyone who doesn't register as a match to them.

          But using the 95% confidence level at McGee Y Utility returns a most recent common ancestor at 960 years ago.

          The 50% confidence level returned 540 years ago, which is closer than anyone else has ever compared to me.

          Because our mismatch markers are all very fast compared to the average for the 37 markers, I figure that my specific genetic distance of 6 at 37 markers is equal to about genetic distance of 3 or 4 average speed markers at 37 markers, which is almost a real match.

          960 years actually makes sense to me. True and old.
          Last edited by benowicz; 16 November 2016, 09:16 AM.

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          • #6
            No, that can't be. It must make no difference at all. Tinkering with McGee showed that they return the same time to most recent common ancestor no matter which specific markers are mismatched. This is only interesting compared to the lack of interesting things.

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            • #7
              It should be noted that "genetic distance" is a real metric, at least to the extent that you pay attention to what assumptions were made in computing it. Time or generations to the most recent common ancestor, however, is an estimate (starting from the "genetic distance" metric) that depends on many assumptions. Not only does this estimate come with some amount of error that cannot be precisely quantified, it also generates a very wide probability distribution. In other words, "genetic distance" is a relatively straightforward metric. "Time to most recent common ancestor" (TMRCA) is an estimate derived from the "genetic distance" and based on various additional assumptions that can't easily be tested. But TMRCA is formulated in an attempt to be meaningful in a genealogical context, while the "genetic distance" doesn't by itself tell us anything about genealogy.

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