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Adoption Quandry

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  • Adoption Quandry

    I have a couple of questions I'd like to add and the situation can be a bit confusing so I hope I'm explaining it well enough.

    I have been working with an adoptee, MP, who was born in 1943 in England;when she found her English birth mother, she was told her biological father was a member of the Canadian Air Force during WWII, RL. MP's top match is another adoptee, JL, from New Brunswick born in the late 1940's whose unmarried mother was CL but no information was given about the biological father. CL is still alive and did not want to have contact as she has family who were unaware that she had a child before her marriage. MP shares a little over 2100 cM with JL which makes me think they are half siblings. So the first question is, given that MP was born in 1943 in England and JL was born late 1940's in New Brunswick, is there any other possibile relationship besides half siblings?

    MP has other matches in New Brunswick but one, DS, shares 525 with MP and 602 with JL. I have started a dummy tree based on the information in the tree owned by DS. Through researching the New Brunswick archives, I have found that DS (b c 1944) has a 1st cousin once removed who would fit the general criteria of MP's biological father, RL which would make DS and MP 2nd cousins. Assuming JL and MP are half siblings, it would also make DS and JL 2nd cousins. So my second question is does 525 and 602 sound a bit high for a second cousin relationship?

    Looking forward to your comments and/or suggestions.

  • #2
    Is JL male or female,

    Paternal Sisters will always share along their entire X chromosome of approx 196cM (daughters receive fathers entire X)
    Paternal Brothers and sister will not share X (Males receive no X DNA from fathers, they receive fathers Y DNA)
    Maternal siblings regardless of gender, will share anywhere between 0 and 196cM on X, with 0 and 196cM share being rare, usually it is somewhere in between due to the random recombination of mothers two X chromosomes to form a unique maternal X to each son and daughter.

    Just keep in mind that Aunt/Uncle to Niece/Nephew can also share between 0 and 196cM on X and can be the same around the same age.
    This relationship also shares with in the same range of half siblings.
    Last edited by prairielad; 7th April 2019, 02:20 PM.


    • #3
      Thanks for the reply. JL is male; sorry if I somehow confused you but I forgot to add that these matches are all on Ancestry so there is no X. The numbers I quoted were all autosomal.


      • #4
        If they (JL and MP) are not half-siblings, what could they be?

        Check here:
        • full siblings (no; different mothers)
        • grandparent-grandchild (no; age)
        • aunt-nephew or uncle-niece (no; one of them should have a full brother at least 15 y older, who would be the father of the other one ... probably not)
        • very unlikely great-aunt and great-nephew (no, age)

        Sherlock Holmes is teaching us: "How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?"

        Also, the relationship with DS is almost the same (525 and 600), probably the same kind of relationship with both JL and MP.

        It is almost impossible, that DS is a 2C. (Unless there is another link in the tree, adding more cM. Endogamy?) With one person, ok, could happen maybe; but both of them?

        Half-1C, or 1C1R is way more likely.


        • #5
          Thanks so much Emona; I was on Sherlock's side myself but just wanted another opinion. I have the shared cM chart as a permanent fixture on my desk.

          I have actually found two possibilities for RL - the one described above which would make them a 2nd cousin to DS which, I agree, seems unlikely given the numbers but the other one seems even more improbable because it would make DS a 5th cousin and, more importantly, it would make another fellow who I shall refer to as JL2 a first cousin who MP only shares about 121 cM with. Except for MP, we're talking about Acadian lineages here so I'm sure JL and JL2 would be matches but thus far I've been unable to find out for sure whether they are or how much they share. The surname of the biological father is very common in Acadian New Brunswick but I still wonder how many of them we could find who had been in the RCAF during WWII


          • #6
            I have just thought of another piece of information which might potentially affect the numbers we're seeing. In the scenario I described where MP and JL would be a 2nd cousin to DS sharing what looks like too much DNA (525 and 602), would it make a difference if their bio father, RL, was a double 1st cousin to DS? In other words, her great-aunt on her mother's side married her great-uncle on her father's side. Adds another dimension to the puzzle


            • #7
              Without actually seeing the family tree, I am not sure who is who anymore.
              Does it mean that
              • two sets of DS's great-grandparents,
              • are at the same time two sets of JL's and MP's great-grandparents?

              That would certainly explain the quantity of shared dna.
              Estimating over the thumb: average 233 cM between 2nd cousins, x 2 = 466, this is close enough.


              • #8
                Thanks again Emona for taking an interest. If my assumption about the identity of MP and JL's father is correct, they would share two sets of great-grandparents with DS. As the range for second cousin is actually 45-515, I thought 525 and 602 could be, as you say, close enough.