GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2006-07 > 1153806157
Subject: Re: [DNA] What confidence level?
Date: Tue, 25 Jul 2006 05:42:37 +0000
It depends on the paper trail. Let me say that again. It depends on the paper trail. If you have an iron clad paper trail on both sides for seven generations then you would have reason to believe that even a 30/37 match is indeed a match. More markers? No. My first step would be to find a 4th or 5th cousin of each man and have them tested at 37 markers. This will give you better numbers for prediction of the founder haplotype. Then you can look at each of the four purported cousins' genetic distance from the founder.
-------------- Original message from Vincent Vizachero
> If two men suspect that they are seventh cousins (i.e. have a common
> ancestor eight generations ago) and undertake a pair of 37 marker Y-
> DNA tests, at what point do we suggest that the results do not
> support their hypothesis?
> If their results are a 30/37 match should we suggest that the DNA
> does not support the hypothesis, or rather that the DNA is
> inconclusive and they should undertake more testing with additional
> cousins if possible?
> Assuming that we test many such pairs of men who ARE (in fact)
> related, about 95% of the time they will have a genetic distance of
> three or less. But about five percent of the time they will have a
> GD of four or more, and maybe a GD as much as eight. So clearly a GD
> of seven IS consistent with the stated relationship, albeit at a low
> confidence level.