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Question on DNA matching unknown parent

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  • 08-06-2020 8:49am
    #1
    Rmulvany
    Registered Users Posts: 214 ✭✭


    Hi all,

    Have a question here, hopefully I can get my question across clearly.

    Trying to help someone out but am not sure if I can give a clear answer so you might be able to help!

    The man in question was adopted at birth and has no records for the father's name.
    He was successfully able to trace the birth mother but this did not provide the information on the father.

    His son had tested on Ancestry and 23&me DNA sites and got some matches that seemed to relate to the unknown paternal line.
    From conversations with DNA matches and studying the shared centimorgans he was able to narrow down the research to a single surname.

    The issue is there are two brothers in this family, thus two possibilities for the father. The two brothers are deceased so there is no way of asking them who is the father. But they both have sons/children.

    The man's son knows his Y-Haplogroup which would be the same as that of his father and grandfather, but it would also be the same for his granduncle and his sons.

    My question is, if the sons of both possible fathers took DNA tests, would one relate stronger than the other and signify which is the father?

    Hope that the above is follow-able.

    Ryan


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    #2
    pinkypinky
    Moderators, Society & Culture Moderators Posts: 6,622 Mod ✭✭✭✭pinkypinky


    So presumably we've a situation where this man is either a half-brother or a first cousin of the people whose father/uncle are the candidates?

    Yes. You'll need to test one from each group and then reviewed the shared centimorgans for the relevant relationships.

    Genealogy Forum Mod



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    #3
    Rmulvany
    Registered Users Posts: 214 ✭✭Rmulvany


    Apologies, I should really think things over more before I post.

    I had a better look at the situation and the shared cM chart.
    I've added in example names to avoid confusion

    Adam has tested his DNA and is trying to trace his grandfather.

    There are two possibilities:
    Mick or Paul.

    Mick's son Rob is testing his DNA so that the relationship can be looked into.

    The shared cM between Rob's and Adam should point to one of the below theories:

    1.
    The shared cM is between 492 - 1315.
    Rob is Adam's Half-Uncle.
    Rob's father Mick is Adam's grandfather.

    2.
    The shared cM is between 62 - 469.
    Rob is Adam's Hald 1st Cousin Once Removed.
    Rob's father Mick is Adam's granduncle.
    Rob's uncle Paul is Adam's grandfather!

    Am I correct in this hypothesis?


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    #4
    pinkypinky
    Moderators, Society & Culture Moderators Posts: 6,622 Mod ✭✭✭✭pinkypinky


    I'm still confused.

    And we are assuming here that Adam's father is another child of Mick or Paul, but definitely not Rob.

    Why do you have a range for the cM?

    ie: what's shared cM between Rob and Adam?

    Genealogy Forum Mod



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    #5
    Rmulvany
    Registered Users Posts: 214 ✭✭Rmulvany


    I was using the shared cM tool from DNApainter.com

    Apologies, Adam's dad is known, he is looking for his father.
    Adam is the basis because he has existing DNA testing completed.

    We know that Adam's grandfather is either Mick or Paul.
    The closest relative to either of these men is Mick's son Rob.
    He is taking a DNA test.

    I am trying to get my head around how to interpretative the results when they come.


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    #6
    pinkypinky
    Moderators, Society & Culture Moderators Posts: 6,622 Mod ✭✭✭✭pinkypinky


    Right, ok. I think just wait to see what the number of centimorgans is and then looked at the shared cM tool again.

    Genealogy Forum Mod



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    #7
    Pistachio19
    Registered Users Posts: 473 ✭✭Pistachio19


    Would the adopted person, Adams dad, not just do the DNA test to see what his match is with Rob. It might be easier to narrow it all down without the extra generation.


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