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genetic distance for siblings

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  • genetic distance for siblings

    My sister is my only match at the HVR1-HVR2 regional coding level and her genetic distance is listed as "2". Please clarify how a direct sibling can be a genetic distance of "2"? Or is that an error?

  • #2
    Originally posted by globalrcg View Post
    My sister is my only match at the HVR1-HVR2 regional coding level and her genetic distance is listed as "2". Please clarify how a direct sibling can be a genetic distance of "2"? Or is that an error?
    FTDNA counts some highly volatile markers as mutations and they sometimes incorrectly count a heteroplasmy as 2 steps. This is the most likely explanation for a 2 step difference. Occasionally a new mutation does occur and 1 step differences are rare but not unexpected.

    I posted last year about sisters who were 4 step differences: 1 new mutation, 1 heteroplasmy and one difference at a highly volatile marker that was counted as 2 steps.

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    • #3
      My sister is not a match?

      Well, I have 3 heteroplasmies (oddly) -- one in HVR and two in coding region. Otherwise I am identical to rCRS. My haplogroup used to be H2a2a1, not it has been "downgraded" to simply H. I have 7 full-sequence matches, all 3 steps from me. does not include my sister.

      My sister has no heteroplasmies and her haplogroup is H2a2a1. She has 305 matches, many with 0 step differences from her. I am not one of her matches.

      It seems to me that I should be 3 steps away from EVERY person who is identical to the rCRS; that includes my sister and many others. Why are my 7 matches closer than my sister---(by the way, my heteroplasmies are all "private" and i do not believe are shared with anyone; my 7 matches are definitely not anywhere near close relatives).

      Family Tree has NO explanation that I can find about how they calculate matches, especially in the case of heteroplasmies.

      My results have changed over time---at one point, my sister WAS listed as a 3-step match, but no longer. Can anyone explain?

      Thanks

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      • #4
        Originally posted by Violet View Post
        Well, I have 3 heteroplasmies (oddly) -- one in HVR and two in coding region. Otherwise I am identical to rCRS. My haplogroup used to be H2a2a1, not it has been "downgraded" to simply H. I have 7 full-sequence matches, all 3 steps from me. does not include my sister.

        My sister has no heteroplasmies and her haplogroup is H2a2a1. She has 305 matches, many with 0 step differences from her. I am not one of her matches.

        It seems to me that I should be 3 steps away from EVERY person who is identical to the rCRS; that includes my sister and many others. Why are my 7 matches closer than my sister---(by the way, my heteroplasmies are all "private" and i do not believe are shared with anyone; my 7 matches are definitely not anywhere near close relatives).

        Family Tree has NO explanation that I can find about how they calculate matches, especially in the case of heteroplasmies.

        My results have changed over time---at one point, my sister WAS listed as a 3-step match, but no longer. Can anyone explain?

        Thanks
        Thank you for sharing your experience!

        Have you tried to get an official explanation from FTDNA by a web request or a phone call ?

        Mr W

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