GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2003-12 > 1071201877
Subject: Re: [DNA] I Need the Experts' help
Date: Thu, 11 Dec 2003 23:04:49 -0500 (EST)
> The question is this: Is member 8134 related to the other members 6517, 6519,
> 6710 even though there are six mismatches with four of the mismatches on fast
> movers over a period of 500 years and 13 and 15 generations to the MRCA?
The exact match of 6517 and 6510 implies that they are both exact
matches to their known MRCA Joseph Hutchinson. That means the
mutations would have to be confined to 19 transmissions (13
up from 8134 and 6 down to Joseph). Given the average mutation
rate of 1/500, the probability of finding 6 or more mutations in
19 transmissions is only 0.05%. It's not utterly impossible, but
it's VERY unlikely.
Note that this situation is different from the one where we have to
estimate the time from the MRCA. Here we have a hypothetical lineage
and are asked to estimate its likelihood. In this case, the fast and
slow markers don't matter because we have a fixed number of
generations and an average rate per generation over all the available
markers. In effect, we are counting any possible combination of 6 or
more mutations in favor of the hypothesis and, conversely, counting
any possible combination of 5 or fewer against the hypothesis.