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YDNA37 Questions?

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  • YDNA37 Questions?

    I have recently took a Y-DNA37 test with FTDNA just to start off finding matches and what not for my Haplogroup.
    So far I only have one match (with a Sicilian Man) with a 'genetic distance' of 2. What does Genetic Distance mean?
    I believe this is a match at the 12 markers and I have no further matches at 25 or 37, is this unusual?
    Also please correct me if im talking rubbish, I am new to all of this!
    My Haplogroup is I-M223 and I can post any further information such as STR and SNPs if you think this will be of assistance.

    Thanks in advance,

  • #2
    When they test your Dna at various markers (12, 25, 37, 67, or 111), they look at how many times a given Dna sequence repeats at these markers. It might repeat something like 14 times, 9 times, 20 times, etc. it varies.

    Usually the number of times a DNA sequence repeats at a given marker goes unchanged from father to son. However, every several generations or so, there may be a slight change in one of the markers. For example, a sequence that repeated 14 times, may now repeat 15 times. This difference between 14 and 15 counts as a genetic distance of 1.

    If the sequence is thought to have originally been 14, and it is now 16, then that would be a genetic distance of 2 because it would be thought that there were two separate mutations - that first it went from 14 to 15 at some point and then in a later generation it went from 15 to 16.

    So your results are compared to others to see if you match at these markers. In your case, a genetic distance of 2 probably means that you differ at two different markers by 1.

    A genetic distance of 2 is not considered a match at 12 markers, so you are probably matching this Sicilian man at 25 or 37. However, it is difficult to say how far back in time you would have shared a common ancestor. Have you looked to see if you match him with Family Finder too?

    By the way, you can change the number of markers on your results page to see your matches at different levels: 12, 25 and 37.
    Last edited by Dabney Carr; 27 July 2016, 11:40 AM.


    • #3
      Let me add to the above explanation by Dabney Carr.

      FTDNA offers a tool TiP (FTDNATiP) that would tell you likelihood of being related to your match, as those probabilities would also depend on which markers the differences are (not all mutations happen with the same frequency).

      See Family Tree DNA Time Predictor (FTDNATiP™).

      Also enter FTDNATiP in the search box of the Family Tree DNA Learning Center as thre is some additional information there.

      Mr W


      • #4
        I do not believe 37 markers is enough to work with matches between surnames.
        At least in most cases 67 or 111 markers are required . Your match may well be just a random match and not real.