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Triangulating DNA results

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  • Triangulating DNA results


    I am trying to trace my grandfathers biological father.

    I had one of my uncles who represent a direct male line take the YDNA 37 test (later upgraded to the YDNA 67 test) plus the Family Finder test.

    I had one of the expected fathers sons take the test but there was no match between the two results.

    I have had a second uncle tested and he matches my first uncle. The test undertaken was the YDNA 37.

    Neither of them is a match to the male who took the test to determine my grandfathers potential father.

    As Im unlikely to find another male to test of the expected fathers family to triangulate thier results (ie to ensure that he is a descendant of the expected father) can I use a Family Finder test on one a female of another line to rule out whether the person we tested wasnt a biological son of the potential father?

  • #2


    • #3

      I am not familiar with the Family Finder test.

      But the Y-DNA test results are the results that you get.

      Y-DNA provides the straight and narrow truth.

      And then it is up to you to figure out what that truth could mean.

      I really am a friendly person, to you, but the facts are the facts.



      • #4
        The obvious answer is that the "expected father" is not the father!

        Now, you can get a daughter preferably, or granddaughter (if no daughter is living) of the "expected father" AND one of your uncles to do the Family Finder Test and it will definitely show if they are close relatives. It's best to test people who are closest as regards no. of generations to your target person.

        A Family Finder test finds cousins in all lines, but the more distantly related two people are, the greater the chance that they don't have any segments of DNA from a particular common ancestor that are long enough to meet the testing standards.

        You should get your uncles (or aunts, it doesn't matter with Family Finder) tested anyway, because it might lead you to discover your true great-grandfather. But it might be a waste of money testing a descendant of the "expected father", as Y-DNA is clearly saying he is not the father (except in the unlikely event that the person you tested wasn't his son either!)


        • #5
          Thanks for the responses.

          Ive upgraded the test results to YDNA67 and found the same names as the earlier testing levels - Knight and Wilkerson on our direct line and no relation to the other family. From other discussions even at those levels of testing those names mean little for the last 300 years worth of ancestry unless there is a surname match which there isnt for us.

          Yes I understand the obvious "hes not the father" and thats not a concern. Eliminating all the possible reasons for the result and applying a more rigorous level of triangulation will probably only confirm that hes not the father but Id like to know that before I present the findings to the family.


          • #6
            I would definitely do the Family Finder test some aunts or uncles. I had a similar situation. My cousins Y-DNA test came back matching Hampton and Hollingsworth, not Mobley as we expected! I joined both surname projects, and the administrator of the Hollingsworth project informed me that those Hollingsworths who matched Hampton were from an NPE in Virginia in the 1700s.

            Suspicious circumstances and a Hampton neighbor led me to believe that my 2nd great-grandmother had an affair with this Hampton or his brother who lived close by. My mother had already done the Family Finder test. I eventually located a descendant of one of the two brothers to do the Family Finder test. When his results came back, he matched my mother at the 3rd cousin level, sharing 3 segments with her, one about 40 cM long. He shared only one segment about 13 cM long with me and none at all with 2 of my cousins who tested. So, you see the importance of testing the oldest generation.


            • #7
              If you test your uncles/aunts, they might by chance have close matches who will reveal the true father.


              • #8
                Thanks moberly

                A fascinating story!


                • #9
                  I'm sure everyone who has been reading this forum for 2 or 3 years is sick and tired of the story! But we always get new people here who are dealing with similar situations.


                  • #10
                    Hi again

                    Ive just found another family member who is the brother to the original person I tested who is willing to take the YDNA37 test.

                    Once it confirm the original result Ill move onto trying to find the biological father (the proverbial needle in many haystacks)


                    • #11
                      You could try to match your DNA to your uncles' DNA through the Family Finder test. You should show a match to them through your father's mother's side of the family, at least. Also do a FF test on the suspected relatives' (looks like you are testing grand uncles, sons of the suspected great grand father). If they show up as matches to you, you will at least have a possible starting point in the needle in a haystack search. If they don't match you, then you'll have to go looking for another needle or haystack.

                      Hopefully there won't be any intermarrying back along the track so that they don't show up as distant cousins.