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Mystery great grandmother

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  • Mystery great grandmother

    I have spent a lot of time trying to determine the ancestors of my mother's paternal grandmother. She died young and did not leave very much documentary evidence.

    I thought that I might be able to get a line on people who are related to her using X-chromosome segment matching. I have my mother's kit on FTDNA and by mother's brother also tested on FTDNA. My strategy is that my mother inherited x-dna from her father's mother and from her mother. My uncle, on the other hand, should have x-dna only from their mother.

    So, if I can find people who match on x-dna to my mother, but not to my uncle, this would suggest that they might share x-dna with my mother's paternal grandmother. I know this sounds complicated. Is this a good strategy to pursue, or am I missing something?

  • #2
    Possible, but using X matches alone, without a strong autosomal match, seems to be difficult. And you have to be sure the X segments are long enough to be "significant" -- which I expect means at least 10-15 cM.

    The way I would attack the problem is to put all the relevant kits on GEDmatch and look for kits that match both your mother and your uncle on the same segment(s), looking especially for matches predicted to be no more than 2 or 3 generations removed. Testing known cousins would help too. The more known relatives whose kits can be compared with your matches, the more powerful the method becomes. A lot of patience is usually required.


    • #3
      Unfortunately, I don't have direct access to my uncle's kit. He's no longer alive and I don't know who has access to his kit on FTDNA, if anybody. I've uploaded my mother's kit to GEDMatch and I've uploaded all of the data I have available to DNAGedcom. I will try to get access to my uncle's kit and download his DNA files, if possible.

      My mother has about 4,100 matches and what makes things more complicated is that her ancestors have lived in the same rural area for 200 years or more and are heavily inter-married. This means that many people who match to her often match several different ways. That makes it hard to pinpoint a connection to the elusive grandmother. I was hoping to use X-DNA to limit the selection to people who are more likely to be directly related to the grandmother.

      I know that this mystery grandmother had a daughter and possibly has some female descendants along the maternal line, which means that an mtDNA test might turn up at some point. Any other suggestions are appreciated!