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Male with massive X-match - error?

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  • Male with massive X-match - error?

    I have one new peculiar autosomal match. I am male. The match is 36cM total, largest segment 10cM - not very close. This kit does not match my mother's kit. Yet in the Chromosome browser, it shows that I match this person almost the entire X segment (length is shown as 193.95cM). That seems bizarre. Aside from my Mom and her brother, I have no other matches with even a 10cM X-match. Is this X-match accurate then, or it is it perhaps an FTDNA error? Thank you.

  • #2
    So, are you saying at GEDmatch you did a one-to-one compare (which is autosomal) with your mother's Kit#; and then, secondly, you also did an X one-to-one compare, and your mother did not match on that either? Since the X, as you already seem to know, cannot pass through 2 successive males..............
    Last edited by Biblioteque; 10th December 2018, 05:26 PM.

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    • #3
      There have been a few reports of seemingly impossible X matches recently. At least some of them have been declared data errors by FTDNA, but exactly how that could happen has not been revealed, as far as I know. Sure sounds like you have another one!

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      • #4
        Contact FTDNA Contact Us / Open Request form and have them look at kit(s).
        https://www.familytreedna.com/contact

        Only reason I can think of for error is one of the kits being compared could be a pseudo kit (ie like a Gedmatch Lazarus kit) that someone created (incorrectly) and uploaded via the transfer utility .

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        • #5
          Originally posted by Biblioteque View Post
          So, are you saying at GEDmatch you did a one-to-one compare (which is autosomal) with your mother's Kit#; and then, secondly, you also did an X one-to-one compare, and your mother did not match on that either? Since the X, as you already seem to know, cannot pass through 2 successive males..............
          No, the kit is not on GEDMatch. At FTDNA I match the kit but my Mom doesn't. I don't know what FTDNA thinks her X-match would be to this kit. Also to correct one point - the X-match is 195.93cM - I mixed up the digits earlier.

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          • #6
            Originally posted by prairielad View Post
            Contact FTDNA Contact Us / Open Request form and have them look at kit(s).
            https://www.familytreedna.com/contact

            Only reason I can think of for error is one of the kits being compared could be a pseudo kit (ie like a Gedmatch Lazarus kit) that someone created (incorrectly) and uploaded via the transfer utility .
            Whatever the reason, it sounds a bit off and I will contact support. Thanks.

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            • #7
              Originally posted by Archdale View Post

              No, the kit is not on GEDMatch. At FTDNA I match the kit but my Mom doesn't. I don't know what FTDNA thinks her X-match would be to this kit. Also to correct one point - the X-match is 195.93cM - I mixed up the digits earlier.
              Is the match with a female?
              Last edited by georgian1950; 11th December 2018, 11:06 AM.

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              • #8
                Originally posted by georgian1950 View Post
                Is the match with a female?
                No, the match is male.

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                • #9
                  Originally posted by Archdale View Post

                  No, the match is male.
                  Now that is curious, since males only have one X-chromosome. That means both of you match exactly on your X-chromosomes. If you were comparing with a female, she would have two chromosomes and you could be getting a half match by matching one or the other at each SNP.

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                  • #10
                    Follow up: I contacted FTDNA and they responded saying that it appears to be a technical error of some sort.

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                    • #11
                      One thing nobody ever seems to mention is the fact that part of the X chromosome recombines with the Y Chromosome.

                      So it is in fact possible for you to inherit part of your X chromosome from your mother's father's father. Your mother's father's X partially recombined with his Y, so one of your mother's X's contains a portion of her father's Y, and then her two X's recombine and you likely get some of that passed onto you.

                      The same holds true for your father. Part of his X and Y recombined, so if you are male, you received part of the X he got from his mother in your Y chromosome, and of course the rest of the Y from him, but even his Y was a combination of his father's X and Y. If you are female, you still receive part of the Y that your father got from his father.

                      Moral of the story is, the X match doesn't filter out the part of the X that recombines with the Y, so it is not a very accurate indicator of anything.

                      Oh, and here's a video that shows how the X/Y recombination is different than the other chromosomes! https://www.biointeractive.org/class...n-y-chromosome

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