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Parents have matches I don't have FF

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  • Parents have matches I don't have FF

    I recently talked my parents into getting their autosomal done to include with mine. So far just my father's has been posted and if I go onto his account and filter the matches by "not in common with" me, he has 33 pages of people that do not show up in my FF results. I am sure this is part of the reason and benefit to getting parents to take the dna tests as well but I was not sure why there are so many more matches he has that did not show up in my results. There are even 2-4th cousins that show up on his that do not show up on mine so it is not taking it back an additional generation as the explanation on all of them. What would cause this?

  • #2
    You only inherit half of each of your parents DNA so it's to be expected that they have many DNA matches that you do not share with them. In the cases of DNA matches that your parents have that you do not, it just means you did not inherit those segments from them which happen to match people here. When I run 'not in common' with me on my mom's account, there are 52 pages out of her 90 pages total. So a bit more than half. Doing the same with my mom on her dad's account, 38 pages of the 76 total are not shared, which in this case, is exactly half. In fact, my grandfather's largest match is 138.08cM, a verified 4th cousin, and that person is not shared with my mom because that DNA did not get passed down to her. It happens. But even though my mom, and I, don't match that person with DNA because we didn't inherit the segments, we still have equal claim to being that person's distant relative based on our paper trail. Paper trail, that person is my mom's 4th cousin 1X removed and my 4th cousin 2X removed, just no shared DNA. If I tested my mom's 2 sisters, there's a pretty good chance one or both did inherit the DNA but they would still have the same genealogical relationship to the match as my mom, 4th cousin 1X removed.

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    • #3
      Originally posted by Littlest bit View Post
      You only inherit half of each of your parents DNA so it's to be expected that they have many DNA matches that you do not share with them. In the cases of DNA matches that your parents have that you do not, it just means you did not inherit those segments from them which happen to match people here. When I run 'not in common' with me on my mom's account, there are 52 pages out of her 90 pages total. So a bit more than half. Doing the same with my mom on her dad's account, 38 pages of the 76 total are not shared, which in this case, is exactly half. In fact, my grandfather's largest match is 138.08cM, a verified 4th cousin, and that person is not shared with my mom because that DNA did not get passed down to her. It happens. But even though my mom, and I, don't match that person with DNA because we didn't inherit the segments, we still have equal claim to being that person's distant relative based on our paper trail. Paper trail, that person is my mom's 4th cousin 1X removed and my 4th cousin 2X removed, just no shared DNA. If I tested my mom's 2 sisters, there's a pretty good chance one or both did inherit the DNA but they would still have the same genealogical relationship to the match as my mom, 4th cousin 1X removed.
      Thank you very much. That makes sense. I guess that is a benefit to getting as many family members tested as you can. It at least opened up new paths for me to try and find a paper trail for. The hard part is finding the common ancestor. Of the many people on here (closest are 2-4 cousins)I am having trouble getting more than the 3 I was able to find relations to and those were hits back in the early 1700s/late 1600s.

      This may be a dumb question...but I have some cousins that married back in the mid 1800s. Would that throw off anything with the predicted relationships? Like put them closer than they really should be (ie. predicted 3rd but should be further back)

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      • #4
        Pedigree collapse can affect matching but not necessarily. Recombination is so variable that you cannot assume absolutes but I have 2 known 3rd cousins at 23andme, one is a known case of pedigree collapse, the other is not:

        3rd cousin, known pedigree collapse, resulting in us being 3rd cousins, 4th cousins 1X removed, 1/2 5th cousins, and 6th cousins:
        -1.62% shared over 7 segments (~120cM)

        3rd cousin, no known pedigree collapse:
        -.49% over 2 segments (37cM)

        As you can see, I share much more DNA with my match that shares my 'kissing cousins' than the one does not.

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        • #5
          Originally posted by Littlest bit View Post
          Pedigree collapse can affect matching but not necessarily. Recombination is so variable that you cannot assume absolutes but I have 2 known 3rd cousins at 23andme, one is a known case of pedigree collapse, the other is not:

          3rd cousin, known pedigree collapse, resulting in us being 3rd cousins, 4th cousins 1X removed, 1/2 5th cousins, and 6th cousins:
          -1.62% shared over 7 segments (~120cM)

          3rd cousin, no known pedigree collapse:
          -.49% over 2 segments (37cM)

          As you can see, I share much more DNA with my match that shares my 'kissing cousins' than the one does not.
          I have a feeling the same is happening with mine. As I try and map out the relations, I was doubting that I had the most recent common ancestor correct on the couple I was able to find but they all are ones that eventually had the
          1st cousin marriage with this line.

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