Thursday, September 11, 2008
Ok, so starting to get a feel for what these DNA tests can do. Ancestry created a new account for each of the tests I bought. I didn't want to have to log into my brother's account every time I wanted to check his results, so I manually entered his results onto my page (since they belong to me, too). Now we're both in the database, so when it gives me my paternal matches, my brother comes up as an exact match. With an exact match, our most recent common ancestor (MRCA) was given as 1 generation back. Which, yes, that's true. But it turns out that it's only a 50 percent certainty. The site pretty much guarantees a 95 percent certainty of a MRCA at 11 generations. So while my brother and I are an exact match and related one generation back, anyone else I find in the database with an exact match could be anywhere between there and 275 years back for a MRCA. The database says anyone off by only 2 or 3 markers is a pretty close match, which would seem to be true, but to find someone related no more than 300 years back from you, you need an exact match. Which considering my branchless tree (at least on the Gorry end of things) is one I need to cross my fingers and knock on wood for.