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  • Genetic Distance match of "0"

    I received a Y-DNA Genetic Distance match of "0". What exactly does this mean?

  • #2
    Before anyone can give you a good answer we need to know how many markers are being compared.

    A genetic distance of 0 on 12 markers could mean a close relative or no connection at all.

    A genetic distance of 0 on 111 markers would mean a close relative.

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    • #3
      This page in the FTDNA Learning Center shows a list of topics on genetic distance, including charts for interpreting genetic distance at each level of STR testing (Y 12, 25, 37, 67, and 111). For example, "If two men share a surname, how should the genetic distance at 37 Y-chromosome STR markers be interpreted?"

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      • #4
        Thanks for the info. I'm a newbie at this so every little bit helps!

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        • #5
          I am new here. I have an exact match with 111 markers with a man with same name. We do not share ANY relatives with same Surname. How is that possible? Thanks so much!

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          • #6
            Originally posted by alabamaauthor View Post
            I am new here. I have an exact match with 111 markers with a man with same name. We do not share ANY relatives with same Surname. How is that possible? Thanks so much!
            To be sure we understand correctly, does this match have the same surname as you? If so, the Most Recent Common Ancestor (MRCA) for your direct paternal line may be several generations back. It sounds like you have compared your family trees, or checked the male ancestors for both of your families, but just in case you have not:
            • Do you and your match show information for your Earliest Known Ancestors for your direct paternal lines in your profiles (as well as surnames and locations)? This information can be important to help identify how matches may be related.
            • Do either of you have a family tree at FTDNA or elsewhere?
            • For an exact match at 111, have both of you researched your direct male ancestors, and then expanded out to any brothers for the male ancestor at each generation? You may be able to determine the connection that way, through such a brother's descendants. It is possible that you have not researched some of these lines yet.
            The Y-DNA Inheritance Descendants Chart (Paternal Line) on this page shows some possibilities for how a Y-DNA match may be related.

            FTDNA's Y-111 chart indicates that your match could be a third cousin or closer to you (also could be a cousin once or twice removed, etc.). In order to find out how you are related to this match, you need to concentrate on the male collateral relatives on your paternal side, and not just your direct paternal ancestors. Collateral relatives include aunts, uncles, nieces, nephews, and cousins at each generation (all siblings, or children of siblings, of your direct ancestors). For Y-DNA descendants, you should look at all the male collateral relatives in each generation, and their male descendants, to see if your match is related through one of those lines.

            Specifically: check back to at least your own paternal 3rd great-grandfather and see if he had any brothers from which your match might have descended, and do the same to find the brothers of your 2nd and 1st great-grandfathers, and your grandfather. If any had more than one marriage, be sure to check sons from those second (or more) marriages. Determine who the male children of those brothers were, and find their male descendants.
            Last edited by KATM; 1 May 2021, 11:42 AM.

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            • #7
              Originally posted by alabamaauthor View Post
              I am new here. I have an exact match with 111 markers with a man with same name. We do not share ANY relatives with same Surname. How is that possible? Thanks so much!
              KATM's answer was great. I just want to add something from my own experience that supports what he said. I have a 110/111 match to a man with my surname, yet he and I don't share a Y-DNA ancestor in common until our trees get back to my fifth great grandfather, who was born about 1750 in Ellicott's Mills (now Ellicott City), Maryland. Similarly, I have a 109/111 match to another man with my surname. He shares that same fifth great grandfather with me and the 110/111 match I just mentioned.

              My point is that you can have close Y-DNA matches who don't share a common Y-DNA ancestor with you until you get pretty far back.

              By the way, even more to the point, I and those two matches have all had the Big Y-700 test from FTDNA (which I highly recommend). That 110/111 match is now a 757/758 match (99.9%), and that 109/111 match is now a 748/751 match (99.6%).
              Last edited by Stevo; 2 May 2021, 08:37 AM.

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              • #8
                KATM you are such a great brain. You are helping with insightful responses in almost all threads in here. You are explaining things comprehensively, even though they are technical

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                • #9
                  Thanks, but I just try to answer the questions if I have any idea of the answers. Sometimes I don't read the post correctly, and end up answering questions that weren't asked!
                  I am now missing breakfast, so that illustrates how I spend too much time answering posts here!

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                  • #10
                    Thanks so much. Are “exact match” and a 111 match the same? I still do not find any common ancestors with our shared surname. My Father gave the DNA sample because my sister and I always believed we had an unknown sibling, given our Father’s rather Randy nature as a young man. He has about “7” lost years unaccounted for from 18-24. Then he became an 82nd AA Paratrooper in WWII. Your answers were so helpful.

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                    • #11
                      Originally posted by alabamaauthor View Post
                      Thanks so much. Are “exact match” and a 111 match the same? I still do not find any common ancestors with our shared surname. My Father gave the DNA sample because my sister and I always believed we had an unknown sibling, given our Father’s rather Randy nature as a young man. He has about “7” lost years unaccounted for from 18-24. Then he became an 82nd AA Paratrooper in WWII. Your answers were so helpful.
                      No, they're not the same. An exact match is one with a genetic distance of zero. You can have 111-marker matches that go as far as, I believe, nine off (102/111). Of course, an exact match at 111 markers, 111/111, is very significant,

                      Of course, an exact match at 12 markers does not necessarily mean all that much (it might, though, especially if the match has your surname). The more markers, the more value matches have, even those that aren't necessarily exact.

                      Here's a chart that FTDNA put out a few years ago that might prove helpful.

                      STR matches and relatedness_genetic distance_dna.jpg
                      Last edited by Stevo; 7 May 2021, 03:13 PM.

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                      • #12
                        Here's another chart from David Vance that might be helpful.

                        Y-DNA_111 y dna str marker_genetic distance and range of generations_David Vance.jpg

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