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X-Match Help

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  • X-Match Help

    Hello everyone, I am an absolute beginner and am trying to help a 70+ gentleman find his biological father's line. He was adopted as a baby but found his mom before she died. I have uploaded his Ancestry Autosomal DNA to FTDNA. The results have revealed his top match (a female) as an X-match. What does this mean? Does it mean that she is on his paternal or his maternal line. I'm so confused and any help would be much appreciated. I apologise in advance if this is a very simple question that I should understand.
    Last edited by Heatherdaile; 1 February 2020, 01:33 AM.

  • #2
    It depends on the size of the x segment. What is the size of the X segment that he shares with his match?

    here is another article to understand about x chromosomes :


    • #3
      Thank you Gattaca for replying and for the link which I'll read. Shared cm are 137 and the longest block is 23.


      • #4
        The man you are helping got his X chromosome from his mother and his Y chromosome from his father. Consequently, any significant X matches have to connect with his maternal ancestry. If the option of doing a Y-DNA test (highly recommend at least Y-67) is available, there is a possibility that his Y DNA might place him in a well-defined cluster where nearly all of his close Y DNA matches have the same surname -- in the event that that happens, you would then have another clue that might help you spot the biological father in census, directory, or similar records. Also recommend transferring his autosomal DNA data to other sites such as GEDmatch, or testing at other sites (watch for sales) in order to increase the chances of finding additional close autosomal matches. There's a fair chance that other members of his biological family are looking for lost relatives too.


        • #5
          Thank you John, I appreciate any guidance I can get. This helps me massively, as he was convinced the match was from his paternal side - it just means we won't waste any more time rebuilding her tree etc etc. Thank you again.


          • #6
            No you haven't established yet that his is a maternal match. FTDNA reports X matches whether they are large or small, and if they are small they are insignificant. You first have to determine the size of the segment(s) that are shared on the X chromosome. Telling us that this man shares 137 cM means nothing as to the question here as it doesn't tell us how much of that is on the X Chromosome.