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My Matches Relatives All Match Me On Same Chromosome

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  • My Matches Relatives All Match Me On Same Chromosome

    I have found a pattern where I see one of my matches and their relatives (who are also my matches) all seem to match
    me in almost the exact same segments​ on the same chromosome. Does this mean it's likely we all inheirted the same segments​ on the same chromosome from a common ancestor?

  • #2
    That's certainly possible. The missing piece is to verify that all of the matches match each other in all combinations on that same segment (the endpoints need not match exactly). When you have that situation, it's called a "triangulation group", and the presumption is that everybody in the group is very likely a descendant of the same common ancestor.

    Having found a triangulation group, the next step is to compare pedigrees. It often happens that the pedigrees are not sufficiently complete, no common ancestor is immediately found, and the connection is apparently farther back -- sometimes several generations farther back than the predicted relationship would suggest, or even so far back that we never find it at all.