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Paradox on a certain segment

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  • mkdexter
    replied
    Originally posted by mizzoudan View Post
    Is this a paradox, or is it just me?

    Here's the scenario:
    Person A Matches me.
    Person B Matches me on an almost identical segment (ends slightly earlier than person B)

    Person A and B both match my mom on the same identical segments they matched me.

    Person A matches my mom's mom on the same segment.
    Person B does not match my mom's mom at all.

    Is this even possible? How could I inherit a copy of the same segment from both my mom's dad and my mom's mom? Is it possible that I somehow either inherited 3 copies of the chromosome, or inherited both copies from my mom and none from my dad? And if so, how would I verify that this was the case?

    Whether it's actually possible or not, can anyone come up with a reason for things appearing this way?

    All matches mentioned above are approximately 9-10 cM.
    One person matches your mom's father, the other person matches your mom's mother.. thus they will both match your mom. You may or may not inherit the same segments because that depends on recombination of your grandparents' segments via your mother to you. In your case it looks like this recombination affected the length of the segment just enough to end in a different place. That's my guess not seeing your results however you can view them and determine this yourself.

    Since you have your mother's test you should be able to compare your test to your grandmother and that will show you which segments (yours compared to hers) are from your maternal grandmother. Then the opposite, the non-matching areas (minus the black spots in the map), would then be those from your maternal grandfather.

    More info in this PDF, page 7.
    http://forums.familytreedna.com/show...2&postcount=20

    Matt.
    Last edited by mkdexter; 2 July 2012, 09:43 PM.

    Leave a comment:


  • Brunetmj
    replied
    Are A and B known relatives? Or just DNA matches?
    Are you ( lets call you X) and A and B the same generation?
    So in order of generation mommom/mom/you,A,B?
    A couple things come to mind. 9 to 10cM is a relatively small amount, I think almost small enough to be considered chance-
    Another possibity is mommom/mom/you sharing with both sides, paternal and maternal with A and B not sharing both sides. This is not uncommon in founding populations such as FCanadians or Ashkenazi Jews.

    Leave a comment:


  • Guest's Avatar
    Guest started a topic Paradox on a certain segment

    Paradox on a certain segment

    Is this a paradox, or is it just me?

    Here's the scenario:
    Person A Matches me.
    Person B Matches me on an almost identical segment (ends slightly earlier than person B)

    Person A and B both match my mom on the same identical segments they matched me.

    Person A matches my mom's mom on the same segment.
    Person B does not match my mom's mom at all.

    Is this even possible? How could I inherit a copy of the same segment from both my mom's dad and my mom's mom? Is it possible that I somehow either inherited 3 copies of the chromosome, or inherited both copies from my mom and none from my dad? And if so, how would I verify that this was the case?

    Whether it's actually possible or not, can anyone come up with a reason for things appearing this way?

    All matches mentioned above are approximately 9-10 cM.
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