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Archiver > GENEALOGY-DNA > 2005-10 > 1130017600


From: John S Walden <>
Subject: Re: [DNA] "Falling apart"
Date: Sat, 22 Oct 2005 17:46:40 -0400
References: <15.4faa1432.308bd2a1@aol.com>
In-Reply-To: <15.4faa1432.308bd2a1@aol.com>


On 10/22/05, <> wrote:
> I think we need to dig a little bit deeper into this situation. 90% seems
> like an extraordinarily high number, given that Blair's study only found a 20%
> rate for matching less than 23/25 after a perfect 12-marker match.

I think we have two different questions here.
The 2002 question was given and exact match of 12/12 and
and match on surname what are the chances of the match continuing at 25 markers.
And that was the 80%

This question is given a close match at 25 markers where the
surnames do NOT match what are the chances of a close match at 37 markers.
One must throw out certain cases where the family already knows of
a name change is the Y line for any of the various reasons.

I look at it a month or two ago and posted the results.

One definition of this is close as reported by FTDNA.
If I use that and look at just one new case that has come my way
[happens to be the 37 marker results for my son-inlaw]
At 25 markers FTDNA reports matches with a total of
39 "matches" [Zero exact, three at genetic distance of 1
the rest at GD 2]

If I eliminate all common duplicated surnames
and I include only those with a 37 marker tested I am left with
a total of 22.
Of those 22 possible other surname matches FTDNA reports zero
matches at 37 markers.

I believe they will go out to a GD of 4 at 37 markers.
Do others have any better odds.
John W

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