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In layman's terms please

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  • In layman's terms please

    From what I am reading and if I am understanding it correctly, a female cannot be matched to a male with a dna test because of the chromosome differences or visa versa.

    So how is paternity determined for a daughter to a father or a mother to a son? It seems to me if you can determine paternity, then you could determine lineage from daughter to father to grandmother to grandfather etc.

    So please try to explain to me in terms I can understand why a male direct descendant from a family line whose mother is the next link and then the grandfather is the next and all males before that would not give results to find a connection to an ancestoral line.


  • #2
    Re: In layman's terms please

    Originally posted by jr barnes
    From what I am reading and if I am understanding it correctly, a female cannot be matched to a male with a dna test because of the chromosome differences or visa versa.

    So how is paternity determined for a daughter to a father or a mother to a son? It seems to me if you can determine paternity, then you could determine lineage from daughter to father to grandmother to grandfather etc.

    So please try to explain to me in terms I can understand why a male direct descendant from a family line whose mother is the next link and then the grandfather is the next and all males before that would not give results to find a connection to an ancestoral line.

    There are 23 pairs of chromosomes: 22 pairs are what we call the autosomal or the recombining DNA. The 23rd pair is the sex gene.
    Paternity tests uses the autosomal. Those are passed from both mother and father and "mixed" into the child, whether male or female. This mixture generates a new set of 22 pairs. This is the part of the DNA that paternity test companies use.
    The 23 pair, the sex gene, is transmitted to the children, but a male receives X-Y, which is the father's Y-DNA and the mother's mtDNA, while females receive X-X, which means only the mtDNA from the mother. The Y received by the male son, is passed on to his son, while this son (the greatson of the first male above) receives the mother's mtDNA, not the grandmother's (each new child a new mtDNA from the mother). So, the Y-DNA goes down the line while the mtDNA does not go, and the autosomal gets mixed as it goes down...
    As you can see, two different kind of "transmissions" between the autosomal and the sex gene.
    Since the Y is transmitted from father to son, to grandson, to greatgrandson..... practically without mutations, this is the DNA that allows us two compare two males to find out if they descend from the same line.
    Hope this clarified.
    Max Blankfeld
    Vice-President and COO @ Family Tree DNA
    A Gene by Gene Company

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