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  • Genetic distance issues

    I have a genetic distance match of zero with a person on my ydna Ftdna site.
    We have both done a 67 marker test.

    Ftdna does not recognize us at 67 marker , but at 12 marker.

    This same person in ysearch has a genetic distance match with me of 15 ..............what is going on?.

    Also, why doesn't ftdna matching pick us up at 67 marker test when we are zero GD on the result

  • #2
    From where do you know that you are GD0 at 67 markers?

    Comment


    • #3
      Originally posted by Bartot View Post
      I have a genetic distance match of zero with a person on my ydna Ftdna site.
      We have both done a 67 marker test.

      Ftdna does not recognize us at 67 marker , but at 12 marker.

      This same person in ysearch has a genetic distance match with me of 15 ..............what is going on?.

      Also, why doesn't ftdna matching pick us up at 67 marker test when we are zero GD on the result
      I have seen something similar to this in my brother's Y DNA matches. A few months ago he had a match at the 67 marker with a GD of 6. When I compared this match to my brother in the Haplogroup Q project I could see they are really a GD of 5. Then one day, (without me having to even send a message to the help desk) the match in question showed up as being a GD of 5 to my brother. So I'm not sure what the issue with their website is already.

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      • #4
        Originally posted by tommypeters View Post
        From where do you know that you are GD0 at 67 markers?
        my Ftdna site

        it does not show a match when I run only 67 marker , or 37 or 25

        Since it shows we are zero GD at 12 markers and that we both tested for 67 marker would indicate that Ftdna is flawed in stating 67 marker for this person.
        next, why does Ysearch indicate a 15 GD with this same person?...........does ysearch only test the level of 67 marker, because we both tested for 67 markers.
        If this is the case, then ysearch would be more accurate than ftdna
        Last edited by Bartot; 30 July 2014, 02:11 PM.

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        • #5
          Apparently you have a gd=0 at 12

          But you may have a mismatch from there on. For example your gd=15 at 67 markers.

          Most matches at 12 markers do not match at 25, 37, 67 or 111markers. That's why you are told to test for more markers. 12 markers are not a good comparison.

          Comment


          • #6
            Originally posted by Bartot View Post
            my Ftdna site


            Since it shows we are zero GD at 12 markers and that we both tested for 67 marker would indicate that Ftdna is flawed in stating 67 marker for this person.
            I think I misunderstood what you had been originally trying to say. FTDNA shows to what level your matches have tested (25,37, 67,111), or even if they have taken a Family Finder test, or an mtDNA test.

            Like JDP1144 indicated, most matches at 12 marker do not match at the higher levels.

            Comment


            • #7
              Originally posted by JDP1144 View Post
              But you may have a mismatch from there on. For example your gd=15 at 67 markers.

              Most matches at 12 markers do not match at 25, 37, 67 or 111markers. That's why you are told to test for more markers. 12 markers are not a good comparison.
              Then it that case my 67 marker test with the other person should include every 67 marker and indicate correctly what the GD is......it will not be zero that's for sure.

              so, with another person who I have zero GD with Ftdna but has only done 37 marker test is.........5 GD in ysearch from me.

              Clearly the person with 67 marker should not be rated equally with me like the person with 37 marker in ftdna. This is false/flawed GD system by ftdna, leading to a waste of time calling people with zero GD when they are really 15 GD.

              My conclusion to this is ysearch clearly have a superior GD system compared with ftdna.

              Comment


              • #8
                I'm not sure I understand your query.

                You have a 0 GD with someone at 12 markers.
                At 67 markers you do not show up as a match with this person on the FTDNA site. At ysearch you show up as a GD 15 with this person.
                Is that correct?
                A match with someone with a GD of 15 at 67 markers will not show up at FTDNA. It is not considered a match representing a connection in a genealogical time period.

                FTDNA will only show GD of 7 (I think) at 67 markers, as above 60/67 is not considered a close match. They match up to GD 10 on 111 markers. (If FTDNA didn't have a cut off somewhere we would have matches with 1000s of men that are meaningless.)

                At ysearch you can look for matches further afield, to investigate matches that fall out of the "Close match" that FTDNA report.
                This is why FTDNA encourage you to upload your results to ysearch.

                Ysearch is supported by FTDNA, they set it up initially.
                The only difference is maybe one uses Infinite Allele and the other Hybrid mutations to calculate the GD. (I'm not sure what Ysearch uses these days)

                Your FTDNA personal match page will go back to the closest match at a given level, in your case you obviously do not have a close match at 67, 37 or 25 markers with this man and he only shows up in the 12 markers match list.

                FTDNA used to have a page that explained the GD and the closeness of matches, But with all their new improved Webpages and designs, I can't find it anywhere, No wonder people new to this can't find it either.

                Comment


                • #9
                  Originally posted by rivergirl View Post
                  FTDNA used to have a page that explained the GD and the closeness of matches, But with all their new improved Webpages and designs, I can't find it anywhere, No wonder people new to this can't find it either.
                  @rivergirl,
                  Yes, I found this very frustrating too. I liked that handy check box that would give an explanation of the closeness of matches and relatedness on the STRs. I didn't even care that it had to do with sharing the same surname because chances are real slim that another tester was going to have our surname anyway.

                  Well because you mentioned it I decided to try to find it again after I gave up looking for it a few months ago. In the Learning Center under Advanced DNA => Y-DNA =>Y-DNA STR Testing. I think it must have been updated recently, because I really could not find it. Well I'm glad it's back.

                  https://www.familytreedna.com/learn/y-dna-testing/
                  https://www.familytreedna.com/learn/...s-interpreted/

                  Comment


                  • #10
                    Originally posted by rivergirl View Post
                    I'm not sure I understand your query.

                    You have a 0 GD with someone at 12 markers.
                    At 67 markers you do not show up as a match with this person on the FTDNA site. At ysearch you show up as a GD 15 with this person.
                    Is that correct?
                    A match with someone with a GD of 15 at 67 markers will not show up at FTDNA. It is not considered a match representing a connection in a genealogical time period.

                    FTDNA will only show GD of 7 (I think) at 67 markers, as above 60/67 is not considered a close match. They match up to GD 10 on 111 markers. (If FTDNA didn't have a cut off somewhere we would have matches with 1000s of men that are meaningless.)

                    At ysearch you can look for matches further afield, to investigate matches that fall out of the "Close match" that FTDNA report.
                    This is why FTDNA encourage you to upload your results to ysearch.

                    Ysearch is supported by FTDNA, they set it up initially.
                    The only difference is maybe one uses Infinite Allele and the other Hybrid mutations to calculate the GD. (I'm not sure what Ysearch uses these days)

                    Your FTDNA personal match page will go back to the closest match at a given level, in your case you obviously do not have a close match at 67, 37 or 25 markers with this man and he only shows up in the 12 markers match list.

                    FTDNA used to have a page that explained the GD and the closeness of matches, But with all their new improved Webpages and designs, I can't find it anywhere, No wonder people new to this can't find it either.
                    I will try to make it clearer.

                    Me and person A ...........both have done 67 marker test.
                    In ftdna we are 0 GD
                    In ysearch we are 15 GD

                    me and person B ........B only tested to 37 markers.
                    In ftdna we are 0 GD
                    In ysearch we are 5 GD

                    we have a problem,

                    Clearly ftdna do not indicate and ignore my 67 to 67 , 37 to 37, 25 to 25 with matching test with me and person A ......why? ........it is a false reading of zero GD .

                    While at ysearch, they must include all 67 STRs and state I have a 15 GD with person A.

                    there is a problem if A and B persons in ftdna have zero GD with me , while in Ysearch they have 15 and 5 GD respectively with me

                    Comment


                    • #11
                      Originally posted by Bartot View Post
                      my Ftdna site

                      it does not show a match when I run only 67 marker , or 37 or 25
                      If I understand what you are saying. You and person A match 12 of 12 markers.

                      But they don't show up as a match at 25 markers, 37 markers or 67 markers.

                      If I got the above right then it's quite simple to explain.

                      For the 25 markers, you have 3 or more differences so they won't show up. i.e. you and person A have 3 or more differences on markers 13 to 25

                      For the 37 markers you have 5 or more differences between marker 13 and 37.

                      For the 67 markers you have 7 or more differences between marker 13 and 67.

                      Thus person A is not a close match to you.

                      I have hundreds of 12 marker matches with 0 GD. None of these match me at 37, 67, or 111 markers.

                      Comment


                      • #12
                        Originally posted by MitchellSince1893 View Post
                        If I understand what you are saying. You and person A match 12 of 12 markers.

                        But they don't show up as a match at 25 markers, 37 markers or 67 markers.

                        If I got the above right then it's quite simple to explain.

                        For the 25 markers, you have 3 or more differences so they won't show up. i.e. you and person A have 3 or more differences on markers 13 to 25

                        For the 37 markers you have 5 or more differences between marker 13 and 37.

                        For the 67 markers you have 7 or more differences between marker 13 and 67.

                        Thus person A is not a close match to you.

                        I have hundreds of 12 marker matches with 0 GD. None of these match me at 37, 67, or 111 markers.
                        thanks

                        now, in the past Ftdna had 2 systems for GD
                        Infinite method and step method

                        Infinite method was 1 GD difference for every STR which did not match.
                        Step method was how much difference or each STR gave you a GD.

                        example: person A and B tested each for 37 markers.
                        A and B had exactly the same numbers for 36 markers
                        marker ( example) DYS390 was 20 for A person and 23 for B person.
                        The infinite method would indicate a GD of 1
                        The step method would indicate a GD of 3

                        I know Ftdna used both methods at the same....which method do they use know for matches in Ydna?

                        Comment


                        • #13
                          Originally posted by Bartot View Post
                          I will try to make it clearer.

                          Me and person A ...........both have done 67 marker test.
                          In ftdna we are 0 GD
                          In ysearch we are 15 GD

                          me and person B ........B only tested to 37 markers.
                          In ftdna we are 0 GD
                          In ysearch we are 5 GD

                          While at ysearch, they must include all 67 STRs and state I have a 15 GD with person A.
                          Have you compared the marker values for A & B to yourself on Ysearch to get an idea of the genetic distance?

                          Have you compared the marker values for A & B to yourself on a FTDNA site to get an idea of the genetic distance?

                          Do the marker values between FTDNA and Ysearch agree for all three of you?

                          If the three of you are in a common project you should be able to see the marker values. If not you could request that A & B send you a copy of their values.

                          If the values aren't the same on FTDNA and Ysearch that could account for the difference.

                          Comment


                          • #14
                            I believe FTDNA use a "modified step method", meaning that if two persons have 20 and 23 as you write it depends on the STR how much this difference will contribute to GD. If it's a very unstable STR that has very fluctuating values from generation to generation at least they should only "rate" that difference as 1 when adding GD. If it's a marker that usually keeps its value from generation to generation and mutations are unfrequent, 3 should be added to GD.

                            I haven't read any official statement from FTDNA if they use this method or not, only second-/third-hand info that it is how they calculate.

                            Comment


                            • #15
                              Originally posted by Bartot View Post
                              thanks

                              now, in the past Ftdna had 2 systems for GD
                              Infinite method and step method

                              Infinite method was 1 GD difference for every STR which did not match.
                              Step method was how much difference or each STR gave you a GD.

                              example: person A and B tested each for 37 markers.
                              A and B had exactly the same numbers for 36 markers
                              marker ( example) DYS390 was 20 for A person and 23 for B person.
                              The infinite method would indicate a GD of 1
                              The step method would indicate a GD of 3

                              I know Ftdna used both methods at the same....which method do they use know for matches in Ydna?
                              In the Learning Center. https://www.familytreedna.com/learn/...etic-distance/

                              Comment

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