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Match at 37 Marker Exact Match, what does this mean?

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  • #16
    Originally posted by MMaddi View Post
    Well, then he's wrong. A 37/37 match probably indicates a common ancestor within the last 200 or perhaps 300 years. It may even be a first or second cousin.

    If you're able to contact your exact match, there's no harm in comparing family trees. You may find a clue that establishes some sort of connection.
    can we vote you in as our Project leader and vote him out ?

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    • #17
      Hello,

      You may also want to see the chart here: http://www.familytreedna.com/faq/ans...px?faqid=4#565 It details general time frames for when a common ancestor is likely to be found at different levels of matching.

      For instance an exact 37 marker match has about a 90% chance of being related within the past 5 generations. While a 36/37 marker match has a 90% chance of sharing a common ancestor within the past 8 generations. Since this is based on a bell curve it can only say what is most common.

      -Darren Marin
      Family Tree DNA

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      • #18
        I would follow Darren's advice on interpretation here.

        But on a more frivalous note (yet still with some practical bearing on becoming comfortable with the range of variability when interpreting statistical confidence):

        If Y STR's were an absolutely and invariable indication of TMRCA, shouldn't a perfect match indicate that you are in fact the same person as the owner of the other profile? Shouldn't your 6 year old son have a slightly different haplotype than he did at age 3? How many markers' difference on a 111 marker haplotype could you rack up in 3 years?

        Just jokes, of course.

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        • #19
          Originally posted by Darren View Post
          You may also want to see the chart here: http://www.familytreedna.com/faq/ans...px?faqid=4#565 It details general time frames for when a common ancestor is likely to be found at different levels of matching.

          For instance an exact 37 marker match has about a 90% chance of being related within the past 5 generations. While a 36/37 marker match has a 90% chance of sharing a common ancestor within the past 8 generations. Since this is based on a bell curve it can only say what is most common.
          Hi Darren,

          I'm a bit confused by this. I have two matches at 37 markers with genetic distance of 4. But if I understand the FAQ, there is no way to tell how many markers we match? Couldn't I have 13 on one DYS value and one of the others have 17 on the same DYS? That would create a genetic distance of 4 but match on 36 markers?
          Is there something I've missed here?

          -Kai

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          • #20
            Originally posted by k.o.gran View Post
            Hi Darren,

            I'm a bit confused by this. I have two matches at 37 markers with genetic distance of 4. But if I understand the FAQ, there is no way to tell how many markers we match? Couldn't I have 13 on one DYS value and one of the others have 17 on the same DYS? That would create a genetic distance of 4 but match on 36 markers?
            Is there something I've missed here?

            -Kai
            Look on the "Results" page of any projects you've joined. If you're both members of the same surname, geographic, or haplogroup project, you'll be able to see their haplotype and compare it to yours.

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            • #21
              Hello Kai,

              I usually try to keep it simple for ease of use. You are correct though, it would be possible to have only one of your 37 markers mismatch and equate to a genetic distance of four. This would be highly unlikely to be four individual mutations as we would likely see other markers mutate as well. In cases such as this if you only mismatch someone on one marker and it is greater than a genetic distance of one it is possible that the mutation jumped two alleles in a single mutation event. This means what could look like a genetic distance of two may actually be a genetic distance of one.

              -Darren Marin
              Family Tree DNA

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              • #22
                OK, thank you Darren.

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                • #23
                  My response you your question about 111 marker tests being different between a father and son is a firm no. Your markers will not change. Y chromosomes are the same as any other chromosome when it comes to polymorhisms. They do not change within the life of the person and a change of alleles between generations is very remote. The TMRCA is based on a simple design that does not deal with differences in mutation rates between markers:
                  DYS426 GTT 10-12 0.00009
                  DYS454 AAAT 10-12 0.00016
                  DYS455 AAAT 8-12 0.00016
                  DYS388 ATT 10-16 0.00022
                  DYS392 TAT 6-17 0.00052
                  DYS438 TTTTC 6-14 0.00055
                  DYS393 AGAT 9-17 0.00076
                  DYS393 is AKA DYS395
                  DYS437 TCTA 13-17 0.00099
                  YCAIIa 0.00123
                  YCAIIb 0.00123
                  DYS459 0.00132
                  DYS448AGAGAT17-24 0.00135
                  DYS394 TAGA 10-19 0.00151
                  DYS394 is AKA DYS19.
                  DYS389i 0.00186

                  If you had 100,000 sons, 9 of them might have a change in DYS426. There might be 22 who have a change in DYS388. If you look at the 3 billion basepairs humans have 99% of them are shared. Many cannot be changed without making an ova refuse sperm entrance for fertilization. So, I may agree on TMRCA calculators, but I am not ready to toss out the baby with the bathwater.
                  Originally posted by Frederator View Post
                  I would follow Darren's advice on interpretation here.

                  But on a more frivalous note (yet still with some practical bearing on becoming comfortable with the range of variability when interpreting statistical confidence):

                  If Y STR's were an absolutely and invariable indication of TMRCA, shouldn't a perfect match indicate that you are in fact the same person as the owner of the other profile? Shouldn't your 6 year old son have a slightly different haplotype than he did at age 3? How many markers' difference on a 111 marker haplotype could you rack up in 3 years?

                  Just jokes, of course.

                  Comment


                  • #24
                    I'm in the E1b1b1a2* subclade, and my closest match at 37-2 (one marker off at 2 steps) traces his paternal ancestry to a village less than 10 miles from my ancestral paternal village in the Neidersachsen region of Germany. But we have different surnames. Since hg E is uncommon in that part of Germany, we suspect there was a name change, probably on my side.

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                    • #25
                      Originally posted by 507 View Post
                      I disagree. I have 2, 37 marker exact matches that I'm not related to. Well, no more than any other random person. We ALL share a common ancestor if you go back far enough.
                      I have a feeling (based on the name matches I am getting) that most people are not who they believe they are. It only takes one infidelity on the paternal side over the last 500-1000 years to put ones Y markers anywhere but where one believes. The only way to "know" is for many of your recent male cousins to test and then a map can be made where the "chain-of-custody" is broken.

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                      • #26
                        Originally posted by AJAskey View Post
                        I have a feeling (based on the name matches I am getting) that most people are not who they believe they are. It only takes one infidelity on the paternal side over the last 500-1000 years to put ones Y markers anywhere but where one believes. The only way to "know" is for many of your recent male cousins to test and then a map can be made where the "chain-of-custody" is broken.

                        but whose to say where the error is ? Their last name or mine ? All we know is that we don't match. Whose paperwork is correct ?

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                        • #27
                          Originally posted by 507 View Post
                          but whose to say where the error is ? Their last name or mine ? All we know is that we don't match. Whose paperwork is correct ?
                          If everyone got yDNA tests, then it would be easy. For example, I am doubting whether paper ancestors from the late 1600s are related to me based on DNA. But I have a match to a cousin who connects to my tree in 1727. From that point forward, he and I can be reasonably confident that our paper trail is correct. But any of our other recent cousins need to take a test to verify if they actually connect to our tree. Our preceived family name of Erskine quite possible is incorrect. We are still related but could be Nichols or Tysons or some other family. OTOH - It could be that my great-x grandfather got around and we are all Erskines. As time goes on the truth will become obvious.

                          This DNA stuff opens up a whole social can-of-worms that humans could conveniently ignore in the past. Ignorance was bliss but it slowly becoming impossible.
                          Last edited by AJAskey; 16 June 2011, 03:56 PM.

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                          • #28
                            One can not assume that y-DNA results automatically are those of his entire paper trail patriline, for the very reason you mentioned. All patrilines should be triangulated. Get, let's say, a known patrilineal 3rd cousin to take the y-DNA test. Let's say the two of you have an ultra high resolution match, with a suggested MRCA within the last 200 years.

                            At this point, you can say that your results & his pertain to the patriline, but ONLY back to the MRCA (great-great grandfather). Let's say a known patrilineal 7th cousin then takes the y-DNA test, with the same result as with the 3rd cousin. Then, you can say the patriline has been triangulated back to the g-g-g-g-g-g grandparents & so forth.

                            Be sure to mark such lineages as triangulated.

                            And if they don't match, you have uncovered a non-paternity event (NPE).

                            Timothy Peterman

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                            • #29
                              Originally posted by JohnLloydScharf View Post
                              My response you your question about 111 marker tests being different between a father and son is a firm no. Your markers will not change. Y chromosomes are the same as any other chromosome when it comes to polymorhisms. They do not change within the life of the person and a change of alleles between generations is very remote.
                              Two things:

                              The mutation rates of some Y markers are much faster than you list (e.g. CDYa and CDYb are each quoted at about 0.035). There's a real chance that a father and son will not be perfect matches at 111 markers, but they will match.

                              As to mutations not happening during someone's lifetime: they can and do happen, but on the autosomes. They're called somatic mutations, and are not passed on to offspring.

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                              • #30
                                Don't forget the Haplogroup you can match all or most of your markers but if your not in the same Haplogroup than your not related. At least not in a more recent time frame.

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