Archiver > GENEALOGY-DNA > 2012-03 > 1331505314

From: "Tim Janzen" <>
Subject: Re: [DNA] atDNA
Date: Sun, 11 Mar 2012 15:35:14 -0700
References: <><>
In-Reply-To: <>

Dear Bill,
I agree with Ann Turner's comments. I think it is very important
that everyone gets the big picture about this. This is really a numbers
game. If you have hundreds or thousands of samples with corresponding SNP
chip data for people who all have accurate pedigree charts going back many
generations and who are related to each other within the past 8 to 10
generations then you should be able to link at least some segments to
specific ancestors who lived 8 to 10 generations ago. However, if you are
simply trying to confirm if two people are 3rd cousins using an autosomal
DNA test for each of them then there is a 5-10% chance that they won't share
any autosomal DNA segments. Thus, this becomes an exercise in how many test
results you have to work with. The more results you have (particularly from
multiple lines of descent from the ancestor or ancestors in question) the
more confidently you can link segments to specific ancestors who lived more
than 5 generations. FTDNA took a conservative approach and said that you
can generally use autosomal DNA to go back 5 generations. That is a true
statement. However, it untrue to say that autosomal DNA can't ever be used
to extend lineages beyond 5 generations. You might want to review the
summary of my Youngman project I posted at
85. The testing was helpful in establishing a genealogical link between
people who are 1/2 4th cousins to each other. However, I tested multiple
people (14) in order to come to this conclusion.
Tim Janzen

-----Original Message-----
[mailto:] On Behalf Of Bill
Sent: Sunday, March 11, 2012 2:31 PM
Subject: [DNA] atDNA

One of the points of discussion was FTDNA's statement that you
couldn't confidently go deeper than the 5th generation.
Some on this list felt that they were getting reliable results as
deep as 7 generations.

So I thought I'd pass this information back to the list, and see how
this might affect anyone's opinion on the subject.


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