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  • Surprsingly no match

    My second cousin and I have been researching our common ancestry for many years. Her paternal grandfather and my maternal grandmother were siblings. We both did DNA tests recently with MyHeritage and when I compare the results I get 'No shared DNA segments found'. Does this mean that we don't share any parentage at all? I find that hard to believe. I can't conceive that my mother was not the woman who brought me up, nor that her mother wasn't my grandmother. I could accept that her father might not have been the person we thought he was, but her mother as well? Surely not. If we shared the great-grandmother, wouldn't that show in the DNA? Was she adopted? Most unlikely as that had several other children, all spaced out as you would expect. Her uncle left money her and her three siblings in his will, and refers to them as his nieces and nephews. No suggestion anywhere that one of them was adopted. Might there be some other explanation?

  • #2
    How are you comparing the results, if there are no shared segments? If they truly didn't share segments, that should mean that neither of you show in the other's match list. Have you downloaded the raw data files and uploaded to GEDmatch, in order to do this comparison?

    I don't see a way at MyHeritage to compare two people in the Chromosome Browser, unless they are a DNA match and appear in the match list. Perhaps there is a glitch at MyHeritage, causing it to show your shared segments with your 2nd cousin incorrectly. Have you contacted them to see if they can help?
    Last edited by KATM; 3rd May 2019, 10:19 AM.

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    • #3
      Sorry, I should have made clear I uploaded both kits to GedMatch. That's where I get the 'No shared DNA' message. On reflection, my grandmother having been adopted is out of the question as I have her birth certificate.

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      • #4
        It it unlikely that 2nd cousins would not share DNA. See the following website that shows a 2nd cousin on average shares 233 cM, with a low of 46 and a high of 515. That suggests nobody is at zero.

        https://dnapainter.com/tools/sharedcmv4

        Try your one-to-one again at Gedmatch. Those kit numbers are long and it is very easy to make a typing mistake.

        If you have not made a typo and you have correctly uploaded the correct kits, then examine the matches to the kits. Surely there must be other matches that you suspect are on that line. If one kit shows those matches and the other does not, then probably the other is not a true DNA descendant. NPE (non-paternal events) is covered at this link.

        https://en.wikipedia.org/wiki/Non-paternity_event

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        • #5
          As a curiosity, at Gedmatch, do a one-to-one on the X to see if there are any results there; and please let us know.

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          • #6
            Are either of you able to test your parent or Grandparent associated with this line?
            Or a Sibling of your parent?

            If your Grandparents were only half siblings (shared mother), as half 2C, the two of you have a small chance of not sharing any DNA.
            Testing someone from an earlier generation may shed light on matter.

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            • #7
              PaMarn, since you and your 2nd cousin have both tested at MyHeritage, how does the comparison show there? Are you finding her in your match list, and is she finding you in hers? If so, what are the estimated relationships shown? What does MyHeritage's Chromosome Browser tool show if you compare with her there?

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              • #8
                Originally posted by prairielad View Post
                Are either of you able to test your parent or Grandparent associated with this line?
                Or a Sibling of your parent?

                If your Grandparents were only half siblings (shared mother), as half 2C, the two of you have a small chance of not sharing any DNA.
                Testing someone from an earlier generation may shed light on matter.
                This is what I'm thinking too, according to the SharedCM project, 2C1R is the closest point where a relative may not match. A 2nd cousin being a "half cousin" would put things past the 2C1R equivalence. If nobody from the older generation is available for testing, testing additional siblings on both sides would be another option. If you're half-2nd Cousins, it isn't very likely that everyone is going to fail to match against the same person(s).

                IE if you have 2 other siblings, and none of them match your 2nd cousin, but you do "properly match" against each other, then the 2nd cousin probably isn't related the way you thought she was. This is why they encourage testing "wider" when deeper(older generations) isn't available.

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                • #9
                  Originally posted by PaMarn View Post
                  Sorry, I should have made clear I uploaded both kits to GedMatch. That's where I get the 'No shared DNA' message. On reflection, my grandmother having been adopted is out of the question as I have her birth certificate.
                  This doesn't really guarantee anything. I know of people who've found an ancestor to have been adopted, or the product of a NPE where the father that adopted them was declared on the birth certificate as the father.

                  As suggested you could test older generations if possible, or look at various matches to see if any matches fit in the tree for one or both of the kits as suggested by ech124.

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                  • #10
                    Thanks for your suggestions. I'm not sure how to do a one-to-one on the X Bibilotheque. Can you explain.

                    KATM. My Heritage says 'no matches'

                    prairielad. Unfortunate my s. cousing and I are both in our seventies. There are no living persons of are older generations. We both have elder sisters, neither of whom have yet been tested.

                    What I did try was a GedMatch search for People who match both of our kits, and it threw up 11 kits, all in 5.1 and 5.2 Gen for both of us. Should I be encouraged by this?



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                    • #11
                      In Gedmatch Genesis, look to the right of your screen:
                      Under DNA Applications, the 4th down is:
                      One-to-One X DNA Comparisons

                      There is an answer, it just has to be found..............
                      Last edited by Biblioteque; 3rd May 2019, 03:44 PM.

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                      • #12
                        No match on X comparison either.

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                        • #13
                          No X-match was expected. X does not travel from paternal grandfather to father.
                          (of the supposed 2nd cousin; remember the original explanation: "Her paternal grandfather and my maternal grandmother were siblings.")

                          Testing a third person would probably give a good answer, if you really want to know and accept the truth, whatever it is.

                          A paternal 1st cousin of the 2nd cousin would be my first choice.

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                          • #14
                            We have a common third cousin and another third cousin twice revoved. Would they be worth testing?

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                            • #15
                              Originally posted by PaMarn View Post
                              We have a common third cousin and another third cousin twice revoved. Would they be worth testing?
                              Yes, they could be, although with 3rd cousins at various levels of removal the chances for smaller shared segments to no shared segments increases. Do you know if those 11 shared kits share known ancestors with you and your second cousin?

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