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Y-DNA Close Cousins Don’t Match

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  • Y-DNA Close Cousins Don’t Match

    I am new to DNA testing, so please forgive me if a question like this has already been asked. I couldn’t find it in a search.

    If two known 1C1R are DNA tested, shouldn’t they both have the same y-DNA haplogroup?

    The situation is this: Two brothers – Bob & Joe (both now deceased) - grew up believing they were full siblings. However, autosomal DNA results don’t show any known paternal side matches between them – only maternal matches.

    Bob’s son was tested several years ago at 23 & Me, and his y-DNA haplogroup was listed as R-L21. Joe’s grandson (the son of Joe’s son) did the Genographic test by National Geographic a couple of years ago, and his paternal line deep ancestry was listed as J-M92.

    I realize there may be differences in the results between two different testing companies, but shouldn’t these known close cousins at least share the same letter (either R or J)? Does a result like this mean Bob & Joe did not have the same father after all?

    Thanks for any light you can shed on this.

  • #2
    What is the total cM shared between the two?

    Haplogroups could be incorrect due to number of yDNA SNPs used to determine haplogroup subclade.
    23andmeV4 test tested approx 2,329 yDNA SNPs
    National Geographic test tested around 20,000 yDNA SNPs

    Depending on Autosomal share amount, National Geographic Haplogroup will be less likely to be incorrect if one companies results are not accurate.

    1C1R should share between 141 – 851cM, on average around 439cM
    Half 1C1R should share between 57 – 530cM, on average around 226cM

    My opinion would be to do yDNA testing via FamilytreeDNA, if autosomal results are unclear.
    yDNA 37 will show each other as a match if both share the same patrilineal line, as well as give them a basic haplogroup prediction of R-M269 (if both are R-L21) or J-M172 (if both are J-M92)

    Currently if both haplogroup labels are correct, then there is an NPE somewhere in one line or the other after known common ancestor.
    Most likely being that Bob and Joe did not have the same father if descendants do match via autosomal test, as they most likely would not match on autosomal
    if NPE occurred after this point
    Last edited by prairielad; 5th February 2019, 06:56 PM.

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    • #3
      Originally posted by Newbie487 View Post
      The situation is this: Two brothers – Bob & Joe (both now deceased) - grew up believing they were full siblings. However, autosomal DNA results don’t show any known paternal side matches between them – only maternal matches.
      Do you know of anybody on the paternal side of the family that could be tested on autosomal?

      But from that little bit alone, I'd be inclined to say they have different fathers. Among the paternal line matches you do have, how closely related do they seem to be? Is that relationship estimated or known?

      Bob’s son was tested several years ago at 23 & Me, and his y-DNA haplogroup was listed as R-L21. Joe’s grandson (the son of Joe’s son) did the Genographic test by National Geographic a couple of years ago, and his paternal line deep ancestry was listed as J-M92.

      I realize there may be differences in the results between two different testing companies, but shouldn’t these known close cousins at least share the same letter (either R or J)? Does a result like this mean Bob & Joe did not have the same father after all?
      If they shared paternal line matches on autosomal, I'd say yes. But as they evidently don't? Anybody's game.

      As you appear to also have Autosomal to work with, you might want to check:
      https://dnapainter.com/tools/sharedcmv4

      A 1C1R should fall within 141 – 851cm shared on their atDNA test, with the average result being 439cm.
      A Half-1C1R should fall within 57 – 530cm shared, with the average being 226 as prairielad mentioned already.

      Sadly there is a lot of overlap there so it is very likely the result is going to be ambiguous.

      Comment


      • #4
        Thank you for your help, prairielad and bartarl260. I really appreciate it, and I know Joe’s family does, too. Unfortunately, Bob’s descendants don’t appear to be interested in doing any further testing. Do you think the y-DNA results I mentioned in my original post, combined with the shared cM autosomal results, will help provide some closure on this issue for Joe’s family?

        Bob and Joe had a sister, Ann (now deceased), and all three grew up believing they were full siblings. Based on the autosomal DNA test results of their children and grandchildren, Bob, Joe, and Ann all have many shared maternal side DNA matches; however, only Bob and Ann’s descendants share any paternal side autosomal DNA matches, so far.

        Here are the shared cMs of Joe’s daughters with the close cousin matches of Bob and Ann’s descendants:

        23andMe results

        Bob’s son & Joe’s daughter #1 = 1C -- shared cMs = 8.83%

        AncestryDNA results

        Bob’s grandson is the only representative for him here

        Bob’s grandson & Joe’s daughter #1 = 1C1R -- shared cMs = 159 across 8 segments

        Bob’s grandson & Joe’s daughter #2 = 1C1R -- shared cMs = 124 across 5 segments

        Ann’s son #1 & Joe’s daughter #1 = 1C -- shared cMs = 547 across 22 segments

        Ann’s son #1 & Joe’s daughter #2 = 1C -- shared cMs = 418 across 20 segments

        Ann’s son #2 & Joe’s daughter #1 = 1C -- shared cMs = 575 across 27 segments

        Ann’s son #2 & Joe’s daughter #2 = 1C -- shared cMs = 433 across 19 segments

        Ann’s daughter & Joe’s daughter #1 = 1C -- shared cMs = 468 across 21 segments

        Ann’s daughter & Joe’s daughter #2 = 1C -- shared cMs = 320 across 16 segments

        Two of Ann’s grandchildren have also tested at AncestryDNA. One descends from a third son of Ann’s, and the other descends from her fourth son. As 1C1R with Joe’s daughters, one shares 125 and 134 cMs with Joe’s daughters, and the other shares 305 and 244 cMs with Joe’s daughters.

        Regarding Joe’s daughters’ autosomal results, AncestryDNA puts Ann’s children in the 2nd Cousin category when they should be 1C. Ann’s grandchildren fall into the 2nd & 3rd Cousin categories, respectively. However, 23andMe puts Bob’s son in the 1C category while AncestryDNA puts his son into the 3rd Cousin category.

        When I input these numbers into dnapainter, the 23andMe results show nearly a 50-50 probability that Bob’s son and Joe’s daughter are 1C. However, most of the AncestryDNA results show a low probability that Bob and Ann’s descendants have the expected relationships to Joe’s daughters.

        So, when we combine these close family autosomal DNA results with the lack of shared paternal side DNA matches for Joe’s line of the family and the differences in y-DNA haplogroups between Bob’s son and Joe’s grandson, would this be enough information to tell Joe’s family whether or not he had a different father than Bob and Ann did?






        Comment


        • #5
          My opinion, based on autosomal results, Joe has a different father then Bob and Ann

          8.83% DNA share between Bob and Joe's children is on the low end of 1C, it is roughly 600cM. (rule of thumb to convert % to cM, multiply % by 68)
          Hard to say based on these two results

          I would lean to half 1C between Bob and Joe's children, based on what the following also shows.

          Joe's children to Ann's children also suggest half 1C based on numbers.
          Bob's grandson to Joe's daughter also suggests they are half 1C1R

          Can you see how much cM is shared between Ann's children and Bob's Grandson?

          As mentioned in previous post, I would recommend at least Joe's Grandson to do yDNA 37.
          This may give a surname lead to Joe's father if he is indeed only a half sibling to Bob and Ann

          Comment


          • #6
            Originally posted by prairielad View Post
            Can you see how much cM is shared between Ann's children and Bob's Grandson?
            Yes, I can see the cMs Bob's grandson shares with two of Ann's children at AncestryDNA. The strange thing is those numbers are low, too.

            Bob’s grandson & Ann’s son #1 = 1C1R -- shared cMs = 232 across 14 segments

            Bob’s grandson & Ann’s daughter = 1C1R -- shared cMs = 112 across 8 segments

            The difference with them, though, is they all share DNA matches that link to Bob and Ann's maternal and paternal sides. Ann's other son and her two grandchildren share those matches as well. The paternal matches are fairly close, too, at 2C1R and 2C2R.

            If there are 2C level DNA matches on the paternal side for Bob and Ann's descendants, shouldn't there be at least one paternal side DNA match for one of Joe's descendants (if he shares the same father)?

            Thank you for your insight and guidance, prairielad. It's much appreciated.

            Comment


            • #7
              To have a 2C level match for Joe's descendants, somebody has to test first. That said, I'd expect them to atDNA test first, Y-DNA test later, at least if they're doing it themselves. So atDNA is a good first step.

              The "problem" with that 2C paternal line match, once found with atDNA, is you then have to figure out if they represent the maternal line(relative to Joe's father), or the paternal line. Unless you luck out and find a descendant of another (currently unknown) half-sibling by Joe's father that knows something. A Y-DNA test would be good for helping figure out which line they're likely on.

              In the meantime, a good quality Y-DNA test, and I'd suggest at least Y-67 in reality(Y-37 for whomever the 2nd person is), and check for surnames on possible Y-67+ matches as possible leads.

              If a 1st-3rd cousin fails to match closely @37 markers, they're probably not closely related on the male line, although "weird things" have happened for others with regards to "random mutation is random." BUT 37 Markers is also notorious for having close matches who turn out to not be very close matches at all. Which is why a higher marker count test is advised if you intend "to go fishing."

              Comment


              • #8
                Thank you, bartarl260. The fact that it's even possible these days to find out the surname of an unknown biological father is amazing. We will let Joe's grandson know that he may be able to help his line of the family solve this mystery if he's willing to take a y-DNA test. Thanks again for your guidance and insight.

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