Saturday, 9 January 2010

An exact 25 marker match

I had my DNA analysed just over three years ago, requesting a '37 marker' result. I was somewhat surprised that there were no 37 marker matches for me from all the hundreds of thousands of tests run by Family Tree DNA. I was even more surprised that there were no 25 exact matches either, though there were a couple of 24 matches with the surnames Cox and Jacks. There were also eleven 23 marker matches. Over the months I have been kept informed by FTDNA of any new matches, nearly all of which have been of only 12 markers, which are really of very little significance. Only today have I had an email telling me that there is an exact 25 marker match! The first one! This is a man with the surname Smith.

As yet I do not know where in the world he is. I have emailed him and await a reply. It is just possible that a comparison of the paper trails from our respective family history research may reveal a link between us. At least we may be able to eliminate a common ancestor over a few generations. FTDNA has calculated the percentage chance of a common ancestor for Mr. Smith and myself, a particular McIlhagga, depending on what is called the Genetic Distance between us, shown I gather by the mutation rates of our particular genes.

There is apparently a 37.69% chance of finding a common ancestor two generations back, a 61.17% chance four generations back, a 75.81% chance six generations back, an 84.92% chance eight generations back and a 90.61% chance ten generations back. Their calculation goes back 24 generations when there is a 99.66% chance of a common ancestor. My great-grandmother was a Smith but at present I can't see how that is relevant. I only have four known McIlhagga generations in my line (back from me) so I suppose those can be eliminated. Five generations apparently takes me to a 69.35% possibility of a common ancestor. I wonder what Mr. Smith's paper trail will indicate?

1 comment:

  1. Today I have heard from a Mr. Brown in the USA with whom I have, not a 25 marker match, but a 37 marker match! The FamilyTreeDNA record says we match 37 - 3, which I take it means a 34 marker match. I'm afraid I do not have a male blood relation Brown in my ancestry, at least back to 1795, so my guess is that the link is probably ten or a dozen generations ago. It is somewhat unlikely that a paper trail will be found - a pity! But how interesting that my best matches are with two of the commonest names, Smith and Brown!