Re: Marker Difference meaning -3 men sharing descent of 250 years
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In reply to:
Marker Difference meaning -3 men sharing descent of 250 years
Nancy Stein 10/29/09
This is a more detailed explanation of the ancestral haplotype than the first:
http://genforum.genealogy.com/dna/messages/1405.htmhttp://genforum.genealogy.com/dna/messages/1405.htm
This is even more detailed:
http://www.kerchner.com/triangulation.htmhttp://www.kerchner.com/triangulation.htm
I do not see any reason for genealogists to bother with the TMRCA calculations, unless they are interested in the theory. FTDNA has summarized the conclusions in these guidelines:
http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=12http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=12
http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=25http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=25
http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=37http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=37
http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=67http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=67
However, it, and other useful information, is hard to find through links on the home page. It is best to go to the site map. The link is at the very bottom of the home page.
http://www.familytreedna.com/sitemap.aspxhttp://www.familytreedna.com/sitemap.aspx
They use these for living to living comparisons. However, they are roughly the same as those I use for living to ancestral matches. As an example of problems of living-to-living, if you test enough people, you will probably find two people with 34/37 matches to the ancestral. However, if by the luck of the draw, you tested them before knowing the ancestral, they would be 31/37 matches and deemed "unrelated," if they differed from the ancestral on different markers. This is why FTDNA allows for the possibility of an "in-betweener."