Re: Interpreting DNA results #dna

Pavel Bernshtam

On 2008.07.21, Sandra Krisch <Sandra@...> wrote:

The test results are in. They show that Robert was one of 18 people
who exactly matched Richard on the 12-marker test. Robert was the
only person to exactly match Richard on the 25 marker test. Robert
was one of four people to match Richard on 34 out of 37 markers, but
the only one matching all 25 markers on the 25 marker test.

What conclusions do these data allow us to draw regarding whether --
and more importantly when(i.e. how many generations ago)--Robert and
Richard had a common ancestor?
FTDNA writes that matching 34 out of 37 markers means that the
probability of a common ancestor in up to

4 generations is 4.3%
8 generations is 28.89%
12 generations is 60.38%
16 generations is 82.15%
20 generations is 93.07%
24 generations is 97.59%

As you can see it is a low probability that the common ancestor was
their great-great-grandfather.

But again - it is all about probabilities, not facts

Pavel Bernshtam

[Moderator's Note: Please note that the probabilities computed by
ftDNA take into account which of the 37 markers were the ones that
didn't match. If you have a 34/37 match of your own, you may have
different probabilities listed on your ftDNATiP Report page.
Nevertheless, Pavel's numbers seem more typical of a 33/37
match than a 34/37 match.]

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