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Two Data Anomalies

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  • Two Data Anomalies

    I manage 5 Family Finder accts: mine, my mother, my paternal uncle (proxy for my father who is deceased), my wife and her mother. The data anomalies referenced exist (1) between my matches and those of my mother and uncle, and (2) within my wife's matches.

    (1) Three of my top 10 matches (after my mother and uncle) do not match either of them. These three are projected 3rd cousins to me, and we have 95/71/67 shared centimorgans with longest blocks of 58/38/37, respectively. The 98/58 match is my 4th closest match (including mom & uncle). I cannot figure out how this could occur.

    (2) My wife's father was 50% Italian, 50% German Jewish, and her mother is 100% Japanese. Her kit has been in Family Finder for just over 2 years, and she has over 3,100 matches. She only shares two matches with her mother due to what I understand is an under-representation of Japanese records in the database. Two other matches are known second cousins (sisters) from her father's Italian family. My wife has only two other kits that show as sharing these sisters as matches. That means that over 3,100 of her matches are related to her German Jewish grandmother. I am not surprised by the number of matches from the German Jewish side of the family, but I think the law of averages would suggest that out of more than 3,100 matches she would have more than 4 from her Italian side.

    If you have made it this far, thank you for reading. Any thoughts on one or both if this conditions would be appreciated.

  • #2
    I've never needed to use the Not-in-common with tool before, but I've just done it with siblings.

    For Tester A, the closest matches that are not shared with Tester B (sibling) are:
    Total 84/69/60 Longest 30/24/19

    For Tester B:
    Total 59/58/57 Longest 25/17/25

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    • #3
      Thanks LJP. Based on your input it would seem that maybe this condition is not so unusual, but it still seems like an odd result.

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      • #4
        I manage five accounts: myself and my four full siblings.

        Together we match over 6,000 unique individuals, but individually none of us has more than about 3,300 of those 6,000. This is because our DNA is not identical. For example, I may have received a stretch of DNA from my paternal grandfather, while my father passed the corresponding DNA from my paternal grandmother to one or more of my siblings.

        The same would be true of your father and your uncle. A match that you received from your grandparent through your father was DNA that didn’t match what your uncle received from that grandparent. This is entirely expected. Those matches that are unique to you (i.e. not shared with either your mother or your uncle) are a window into the “other side” of the DNA that your uncle received from his parents. If your father had other siblings you can test, you may find that they match these “unique to you” matches, and it will likely open up other matches where that sibling didn’t get what your father and uncle received.

        The only way your uncle could be a perfect proxy for your father is if they were identical twins.

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        • #5
          Understood, thanks Bob

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