Announcement

Collapse
No announcement yet.

Help with DNA Results

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Help with DNA Results

    To possibly find my wife's biological father she took a Family Finder Test in 2014. Until recently, her matches were insignificant. In October 2017 we had our first breakthrough with a very close 1st-2nd Cousin match, 559 total Centimorgans, 76cms longest block. We emailed this person A(female) who has been so helpful in assisting us get that step closer. Researching the family tree we contacted another person B and today we got our second highly significant DNA match once again FF, with person B, also a female, who we knew was a first cousin to person A. Person A's mother was a brother to Person B's father. Person B's results were much higher in numbers than Person A, namely 1187 total centimorgans, longest block 112. Using a relationship chart, together with family knowledge, we can now say that Person B is either a half sibling or first cousin, to my wife. There is another female, Person C, whose father was a brother to Person A's mother & a brother of person B's father, hence Person C is a first cousin to both A & B. What is our next step and what other relationship do our test show?
    Last edited by BedfontLass; 11 February 2018, 05:51 AM.

  • #2
    It would certainly help to test person C, too.
    If your wife (W) is a cousin to both A and B, then she might be a half-sibling to C.

    This tool https://dnapainter.com/tools/sharedcm
    says that B is very low to be a half-sibling to W.
    A is on the low end to be a 1C to W.

    Have you considered a third possibility?
    (If the ages of the people involved allow it.)

    If W is actually half niece to B
    then she is also 1C1R to A.
    (In this case B's father had an extra child, who happened to be the father of W.)

    One important question:
    who was close enough to the mother of W, 9 months before her birth? Same town, same school/workplace/sport club?

    By the way, how many cM do A and B share?

    Comment


    • #3
      Help with DNA Results

      Thanks for your reply. Yes we have sent a request to person C to do the FF DNA test. Person C we believe is the most likely half-sibling. She is also a first cousin to A & B. A & B share 435 cM, longest 77cM. I have just uploaded B's results to Gedmatch, awaiting results. On Gedmatch one-to-one, W with B, shares 1242.7cM, and W with A, shares 528cM Yes we have looked at other options but ages and dates suggest improbabilities. It all boils down at this stage to C doing the FF test I think? C's father is certainly in the mix, being in the area around time of conception. What do you think?

      Comment


      • #4
        Interesting that A and B share only 435cM - that's quite a bit below the published range for first cousins. I've read that outliers were not included, so maybe the 1C outliers go this low.
        More data is always better So asking person C to test is definitely the next step. And let us know what happens!

        Comment


        • #5
          A and B half-cousins?

          If C is also a low match to A, it sounds likely.
          In case A, B, and C wish to know this detail, they could check their common/not-common matches, and even test a 2nd cousin or two.

          Curiously hoping that C is curious about possible half-sister.

          Comment


          • #6
            Also ... as both W and C are female, the x chromosome will be helpful. See prairielad's reply (#4) to your earlier post "Half Sibling - how to prove" in November 2017

            Comment


            • #7
              Help with DNA Results

              I have looked at the in common with/not in common with tool and can offer the following.
              There are 113 common matches B with W
              There are 43 common matches B with A, with 27 of those common matches also being with W

              On the X to one tool on Gedmatch
              B to W 17.7 cM
              B to A total 88.9 cm (longest 78.4cm
              A to W 0 cM

              Not quite sure what all this means?

              Comment


              • #8
                It is quite late and my mind is slow, but it seems to me that B and W are not daughters of the same father.

                Two daughters would always inherit one X chromosome from their father. (Remember: A man has one X and one Y. If you get Y from your father, you are a son. If you inherit his X, you are a daughter.) Two daughters would share one complete X.

                B and W only share a small segment.
                Waiting for C.

                Comment


                • #9
                  Originally posted by BedfontLass View Post
                  I have looked at the in common with/not in common with tool and can offer the following.
                  There are 113 common matches B with W
                  There are 43 common matches B with A, with 27 of those common matches also being with W
                  <snip>
                  Not quite sure what all this means?
                  I only use the ICW tool when I have an unknown match and I want to see which of my other matches the unknown one might connect with - in other words, the in-common matches provide some clues about where the unknown match might connect to me. As you already have some close matches for W, I recommend you follow them through before torturing yourself with ICWs.
                  If you want to know more about using the ICW tool, try this post by Roberta Estes: https://dna-explained.com/2016/07/21...mily-tree-dna/ She discusses the ICW tool about one quarter of the way through this post. The same post also has a section on the Matrix, which I always use in combination with ICW.

                  Comment


                  • #10
                    Originally posted by BedfontLass View Post
                    On the X to one tool on Gedmatch
                    B to W 17.7 cM
                    B to A total 88.9 cm (longest 78.4cm
                    A to W 0 cM

                    Not quite sure what all this means?
                    I don't have expert knowledge of the X, and I haven't ever used it as an analytical tool. All I can offer is that my maternal 1C shares with me two segments on the X (51.4cM and 43.24cM) and that this is consistent with the amount of X shared by your A and B, who are also first cousins.
                    As Emona says, wait for C's results.

                    Comment


                    • #11
                      A man receives an X chromosome from his mother and a Y chromosome from his father. He passes his entire X chromosome to each of his daughters. He passes his complete Y to each of his sons. All sisters who have the same father will match along the entire length of their X chromosome. It's that simple.

                      A woman, on the other hand has 2 X chromosomes - one that she received from her father and one that she received from her mother and she passes an X chromosome to each of her children, male and female. BUT when she produces egg cells the X chromosome she got from her mother usually gets together with the X she got from her father and they swap a few segments of DNA forming 2 chromosomes that are a patchwork of the chromosomes she received from her parents. This is called recombination. (It occurs with the other 22 chromosomes in both males and females.) So the X chromosome a child receives from his or her mother usually contains segments from each of her parents. Occasionally recombination fails to occur and the child inherits an entire X chromosome from the mother, either the one she got from her father or the one she got from her mother.

                      Comment


                      • #12
                        The chromosomes in each pair can swap segments with each other, including the pair of X chromosomes in a female. In the XY pair of a male the chromosomes are a different size and shape so that they can't get together and swap segments (recombine). The reason for this is that the Y chromosome carries all the instructions for making a male human being and it would be a very bad thing for it to be swapping segments with the X chromosome.

                        Comment

                        Working...
                        X