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  • So what does this tell me?

    I did a quick look through the forums and didn't see an answer so I am posting. Sorry if it's be asked before.

    I had several perfect 25/25 matches. Out of curiosity, I went ahead and ordered the 37 marker test. None of the perfect 25/25 registered on the 37 marker test at all, at any distance.

    So what does that tell me from a genealogy pov?

  • #2
    Originally posted by Worlddan
    I did a quick look through the forums and didn't see an answer so I am posting. Sorry if it's be asked before.

    I had several perfect 25/25 matches. Out of curiosity, I went ahead and ordered the 37 marker test. None of the perfect 25/25 registered on the 37 marker test at all, at any distance.

    So what does that tell me from a genealogy pov?
    It could mean one of two things: (1) The people who matched you at 25 markers didn't test any more than 25 markers, so they wouldn't be listed in the 37-marker matches section, or (2) The match fell apart after the additional markers were tested. For example, let's say you matched 25/25, then none of the additional markers added tested after 25 were matches, such that it ended up being 25/37. That would not be considered a match anymore, so it wouldn't show up anymore on your list of matches. Even a 30/37 wouldn't be considered a match any longer. It's partly the luck of the draw as to which part of the panel the mismatches will occur--it's possible (though unlikely) for them to be clustered in one section, e.g., see DKF's post today here:

    http://forums.familytreedna.com/show...3&postcount=10

    You can tell if any of your 25-marker matches tested more markers if they have (Y37) or (Y67) after their names.

    Chances are excellent that a 25/25 match would hold up to the additional testing resolution, especially if the surname is the same, but it's by no means certain. That's why most serious genealogical researchers will test at least 37 markers, and preferably 67.

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    • #3
      Sorry I didn't mention that in the OP. Yes, the people I matched with did have 37 marker tests. That's the reason I decided to upgrade, to see if we still matched at 37. We didn't. However, none of the 25/25 matches shared my surname. So maybe I should be less surprised we didn't match at 37/37 and wonder more why we matched at 25/25.

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      • #4
        matches

        marvelous question. Please, someone give him a marvelous answer. I want to know it, too.

        None of my 21 1 GD matches at 25 markers made it to 37. None were same surname. None were even in my sub Clade, where the matches had greater GD.

        Now, I understand why to some extent ... convergent evolution. Jacob moves from Tyre to London and Swen from Sweden. Both 3,000 years ago. They will develop characteristics in common that Swen's brother Ivan will not when he moves to that chateau on the Volga.

        But otherwise I don't understand why none of my 21 1 GD matches made it to my 37 and NO ONE matches me at 37.
        Deirwha
        Registered User
        Last edited by Deirwha; 7 August 2008, 04:50 PM.

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        • #5
          How I interpret this stuff...

          In terms of deciding if there is a relationship, the tool used by many people is a utility which displays TMCRA as a percentage of probability for a given amount of time. TMCRA is "The Most Recent Common Ancestor". There is a percentage of probability of sharing a common ancestor with another individual dependent on how many markers differ between the two individuals.

          If there is a 25/25 match then there could be about a 61% possibility of sharing a common ancestor with that person with 4 generations. by 8 generations the likelihood increases to around 85% possible, etc. This is not to say that in this example by 8 generations you necessarily share a common ancestor, there would still be a 15% probability that you do not have a common ancestor. This is also only speaking about the odds of the probability of this occurring and is not a timeline to be relied upon.

          Think of increasing the number of markers tested as though you are to switching to a finer filter. You are now holding up the existing matches you have found to a higher standard. The same process of comparing markers between the two individuals is occurring, but now there are say 37 markers which might indicate differences.

          If you maintain a 37/37 match with an individual you might find that within 4 generations there could be about an 84% possibility of sharing a common ancestor instead of a 61% possibility. Within 8 generations there could be a 97% possibility of sharing a common ancestor. While a common ancestor might be found within an even shorter timeframe than these percentages indicate, there is nothing concrete about these numbers and the common ancestor could certainly be even more distant. Again these are only percentages of probability.

          As matches to other participants fall away when you upgrade to more markers, There is no less a connection to any of the matches, it is an indication that the common ancestor is in the more distant past than the initial tests indicated.

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          • #6
            Originally posted by Deirwha
            marvelous question. Please, someone give him a marvelous answer. I want to know it, too.

            None of my 21 1 GD matches at 25 markers made it to 37. None were same surname. None were even in my sub Clade, where the matches had greater GD.

            Now, I understand why to some extent ... convergent evolution. Jacob moves from Tyre to London and Swen from Sweden. Both 3,000 years ago. They will develop characteristics in common that Swen's brother Ivan will not when he moves to that chateau on the Volga.

            But otherwise I don't understand why none of my 21 1 GD matches made it to my 37 and NO ONE matches me at 37.
            Deirwhat, this is very interesting to me. I have some strange haplotype/clade-designation riddles within my own surname. Sometimes I wonder the extent to which clades may be mis-reported in YSearch or projects, due to clerical error, over-confidence in a prediction, etc.

            You wouldn't mind letting us know your YSearch profile# so we could do a little looking around?

            I'm sure you've already considered it, but my first thought is that these other folks didn't test for deep-clades, and may be reporting as an undifferentiated, predicted haplogroup, whereas you went the extra mile and actually deep-clade tested. Maybe you really do belong to the same clade as these fellows, but they just don't know it yet?

            Sorry if you've already considered this, but it is interesting.

            Jack

            Comment


            • #7
              Good info

              One of my challenges is, as I noted on another post, I am mostly interested in this to find tribal roots. But with a GD of 2 on 25 marker with 21 individuals, some of whom did not show up on the 12 marker, no one on 37 marker, no one closer than a GD of 2 on the 25 marker, no one closer in my clade than a GD of 4 on a 25 marker, I am putting my hopes into the clade basket for now.

              Comment


              • #8
                Originally posted by FredSpringer

                As matches to other participants fall away when you upgrade to more markers, There is no less a connection to any of the matches, it is an indication that the common ancestor is in the more distant past than the initial tests indicated.
                Fred:

                That's an interesting thought. My follow-up question would be as follows. If I matched 25/25 and then tested 37, and assuming none of the 12 additional markers matched, how would that change the TTMRCA calculation. In other words, is the time to most recent common ancestor the same for 25/25 as it is 25/37? If a 25/25 means 61% in four generation, what does 25/37 mean?

                My point is that if one focuses on the TTMRCA ancestor FamilyTree DNA doesn't do much to help. All I know now is that I matched 25/25 and not at all on 37, so how do I know what that means in terms of TTMRCA? You say it's likely "more distant" but just how much more distant?

                After all, 61% in four generations was enough to get me curious; that's better than a coin flip. I've bet money at the horse races on 60% odds. But if you now say, for example, that it only means a 30% odds in four generations I'm likely to take a pass.

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                • #9
                  A useful way of thinking

                  for me too as I plumb my tribal history. 61% may not be immediately useful, genealogically speaking, but it is anthropologically if that match up tells me more about the tribe.

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                  • #10
                    It still may be of value to go to Y Search. At that site, you can vary the number of permissible mismatches. If you allowed up to 8 mismatches for example, you might find that some of your 25/25s show up at 37 markers.

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                    • #11
                      did that

                      At 37 1 person has a gd of 3, 7 a gd of 6, the next nearest a gd of 9. I found it interesting that the finder, Ashkenazi25 had a GD of 4. In fact, if my 393 had been 12 instead of 13 and one of my others been 1 higher I would have hit the Cohen Modality. So, as talked about in another thread, I do sometimes wonder about error. But I can't build on that thought.
                      Deirwha
                      Registered User
                      Last edited by Deirwha; 7 August 2008, 07:42 PM. Reason: related thought

                      Comment


                      • #12
                        Originally posted by Deirwha
                        At 37 1 person has a gd of 3, 7 a gd of 6, the next nearest a gd of 9. I found it interesting that the finder, Ashkenazi25 had a GD of 4. In fact, if my 393 had been 12 instead of 13 and one of my others been 1 higher I would have hit the Cohen Modality. So, as talked about in another thread, I do sometimes wonder about error. But I can't build on that thought.

                        Exactly, now you understand my frustration (and I guess I understand yours). "Where is the wisdom we have lost in information?". All this statistical mumbo jumbo is OK, I understand it. But telling me, as Fred does, that a 25/25 that didn't match at 37 means its "more distant" is good information, but doesn't give me anything to build with and/or to go forward with. I wish FTDNA would do a better job of contextualizing their data.

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                        • #13
                          yes, I guess

                          the question is whether they can. I have a similar beef. But I suppose I might be cautious too if I were trying to establish myself and the credibility of my work without benefit of much of a baseline. It does play at the back of my head a bit that most of what forest people put to the trees is based upon the geographic demographics of people alive today who have taken the tests recently. I puzzles me a bit how one builds a genetic journey without sampling graves in a statistically valid manner. Of course, how would they do that with the cultures that cremated, Dyer? Ok, point. And I just read an article by a respected physical anthropologist taking umbrage with Zawass for asserting he could make a scientific determination based on DNA of relationships among Egyptian mummies because of the difficulty in getting out the DNA. For my own instincts, I am suspecting some of the clades that some have suggested for a recent origin to be much more ancient and therefore less susceptible to pinning down actual migration and "homeland." In fact, I am not so sure I understand the concept of a homeland anymore. It is frustrating, because it is the tribal roots that call to me. I guess we both must be patient. Reminds me of a poster in a former boss' office. Two vultures talking to each other. One says, patience, h__, I'm going to kill something. Oh well, it must be getting late.

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