Archiver > GENEALOGY-DNA > 2004-03 > 1080506810

Subject: Re: [DNA] Some thoughts about the near future
Date: Sun, 28 Mar 2004 15:46:56 -0500 (EST)
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Peter wrote:
> I would think we just need SNP tests of those areas
> which will identify our sub clad. Knowing our sub
> clad and a "sufficient" number of STR markers should
> allow us to only have close matches with close
> relatives. I wonder how many markers is sufficient?

That depends on what you consider a close match and on what
you consider a close relative. If you have 1000 markers
with an average mutation rate of 0.002, then you can be 99%
confident that any exact match is a 1st cousin or closer.
On the other hand, you would expect a typical 1st cousin to
be about 8 steps away. Under the circumstances, you can
be 99% confident that anyone with no more than 8 steps of
difference is a 4th cousin or closer.

Knowing your subclade (note, by the way, the word is CLADE,
not CLAD) will not make much difference in this calculation.

John Chandler

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