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Cousin Matches

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  • Cousin Matches

    Can someone tell me what this means:

    Cousins who match me and my son differently.

    Mary matches me at 46/31 and she is an X to me
    Mary matches my son at 50/30

    What does this mean?


  • #2
    I don't understand where you are finding numbers such as 46/31 or 50/30. We need some context.


    • #3
      Shared Centimorgans/Longest Block


      • #4
        Cousin Matches

        Shared Centimorgans/Longest Block



        • #5
          It might mean that both the other parent of your son and you are related to Mary.

          It would be true, if the other parent of your son and you were from very distinct populations. For example, Amerindian and Dravidian. (Sorry, I could not find a better example of two large populations that are very far apart.)

          However, in most cases it is just a random alignment of DNA that makes such an appearance. Especially if all of you are from one population, for example European. In that case, you and the other parent of your son might have common ancestry hundreds years ago.

          Mr. W.
          Last edited by dna; 19 May 2018, 03:59 PM.


          • #6
            Cousin Matches

            Thank you, Mr. W.
            The son and I are European all the way.

            The thing I would like to be able to discern is whether my son is related to Mary through me or is he directly related to Mary and Mary is also directly related to me. I think you have answered that but when I take the cM down to 1, here is what I see

            Mary and Me
            ch 5 = 2.71
            ch 10 = 1.69
            ch 11 = 1.78
            ch 12 = 1.99
            ch 19 = 22.8
            x = 5.39

            Mary and my Son
            ch 2 = 1.73+2.54
            ch 5 = 2.35+2.39
            ch 8 = 1.61
            ch 10 = 2.09+2.07
            ch 11 = 1.33+2.29+1.78
            ch 13 = 2.12
            ch 19 = 23.79

            Does this change your suggestion above?

            Wish I understood more. I bought a dummy book but it is way over this dummy's head (and deals with plants - not humans).

            Thank you.



            • #7
              Hello Gwen, could you please review your posts? Your original post and the chromosome browser results appear to not match.

              Mr. W.

              I wish my plants were as easy to talk to as people !


              • #8
                It is also better to include the segments start stop points.
                this will show which segments were inherited by son from you.

                Chromosome / Start Location / End Location / centiMorgans (cM) / # of Matching SNPs

                18 / 63775436 / 68384125 / 8.92 / 1458

                Note: Anything under 7cM/500SNPs is likely to be a false segment, especially if it is not found in parent
                Why you may ask....this is due to fact each position tested has two values, a paternal value and a maternal value (We have two of each chromosome, 46 single chromosomes, 23 from our mother, 23 from our father), which is which can not be determined by testing company. The matching algorithm is looking for a matching sequence of single values in a row. the shorter the segment, the more likely it is creating a false segment by zig zagging back and forth between your and matches maternal and paternal values.
                Last edited by prairielad; 20 May 2018, 12:33 AM.


                • #9
                  A great book to get is "The Family Tree Guide to DNA Testing and Genetic Genealogy" by Blaine T. Bettinger.