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  • Gedmatch =0 on 'One to One'

    My 4th cousin and I do not show up as matches in Family Finders. So we uploaded our raw files to Gedmatch. The One to One comparison brings up 0/zero. Is there any tweaking we can do with the numbers?

    We are both females with same last surname.

    Thanks all.

  • #2
    Originally posted by cacitoo View Post
    My 4th cousin and I do not show up as matches in Family Finders. So we uploaded our raw files to Gedmatch. The One to One comparison brings up 0/zero. Is there any tweaking we can do with the numbers?

    We are both females with same last surname.

    Thanks all.
    Try resetting the defaults on Gedmatch to a lower value like 300 SNPs/3 cM. You may have matching segments that are just below the default values. It's also possible that you did not inherit any common segments; as many of half of 4th cousins don't have enough shared DNA to match.

    Jim

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    • #3
      Hi Jim,

      I did the 300 SNPs and the 3cM values: Are the following results good?

      Chr Start Location End Location Centimorgans (cM) SNPs
      1 243048086 244187679 3.8 401
      2 216574684 217883318 3.2 362
      7 13874352 15834996 3.2 610
      8 10366087 12813889 4.5 611

      12 11993379 12974404 3.7 352
      12 107403597 111654550 3.4 754

      15 25522899 27387295 5.0 318

      16 5516245 6195417 3.3 366
      16 12570056 13568419 3.0 377

      Largest segment = 5.0 cM
      Total of segments > 3 cM = 33.2 cM

      Looking more encouraging
      Cindy

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      • #4
        Those segments are pretty far below the usual standard for matching, but would not be uncommon for 4th cousins. I think all you can say at this point is that your matchung segments are consistent with your family records, but do not provide significant additional evidence.

        Comment


        • #5
          Jim,

          Thanks so much for your help and speedy replies!

          Cindy

          Comment


          • #6
            Do either or both of you have parents, aunts or uncles to test? One generation back should be conclusive.

            Comment


            • #7
              At 4th cousins, there is a chance that you don't inherit dna from your common ancestor. Or not the same segments as your 4th cousin.

              I found it here:
              https://sites.google.com/site/wheato...which-dna-test
              Lesson 2.

              Comment


              • #8
                If you don't have anyone a generation closer in to test, you might find the DNA showing up in one of your siblings. All of my older generations have passed, but I had my brother (full sibling) tested and he has several dozen pages of cousins that I have nothing in common with, and the reverse situation being the same for him not matching dozens of my matches.

                Comment


                • #9
                  RE "I did the 300 SNPs and the 3cM values: Are the following results good?"

                  I find that only 10% of the matches at 5 cM and less turn out to be valid the others are just random matches.
                  You have almost 10 segments thus one of them may be valid
                  With out parents to test you need to look for
                  other ways to phase your data
                  Do you, or your cousin, have any children to test?

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                  • #10
                    Yes, both of us have children that could be tested. Thanks much for another explanation.

                    Comment


                    • #11
                      If you test a child then about half of those segments
                      will be in the child's atDNA the other half will be
                      in the half the child did not get from you
                      With phasing you can see both and determine
                      if any of those are possibly valid matches

                      Doing this on both your and your cousin's side will
                      give you the best shot at a valid result.

                      Comment


                      • #12
                        FTDNA

                        JSW:

                        What DNA test do we order for our children?

                        Jane

                        Comment


                        • #13
                          Order the standard Family Finder test
                          I have been surprised by how much more I get done
                          by having family members tested, aunts, uncles cousins and children. Initially I thought it would make no difference
                          Now I see the value and wish I had more.

                          Comment


                          • #14
                            On paper, 4th cousins would share about 0.195% of their DNA or 13.28cM. While you share more than that in total, no one single segment is long enough to be significant - that is not unusual for a 4th cousin but also can be possible for a non-legit match.

                            Comment


                            • #15
                              Since genealogical 4th cousins only have about a 50% chance of sharing half-identical chromosome regions from their common ancestor, you should not be surprised if a known 4th doesn't come back with any shared segments.

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