GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2011-08 > 1313088390


From: David Johnston <>
Subject: Re: [DNA] exact match at 67
Date: Thu, 11 Aug 2011 13:46:30 -0500
References: <005801cc574b$96bb1af0$c43150d0$@dgmweb.net> <CAKWx04SbrJFe_UDuKKBnSY2wxTX2b6BE6KVJmjhjb27M5gHD-g@mail.gmail.com> <950D783B573A4FE78DD7CD26F8C8DB53@jimpc> <CAKWx04SAWri+7oaHsDsp3dUfjY10AY3He7gCgbiNOmdY-o0K1A@mail.gmail.com> <4e43c01b.46b0340a.182f.4774@mx.google.com><009e01cc5853$e3c54d30$ab4fe790$@dgmweb.net>
In-Reply-To: <009e01cc5853$e3c54d30$ab4fe790$@dgmweb.net>


On 8/11/11 1:24 PM, Diana Gale Matthiesen wrote:
> The answer is you cannot, and you cannot because mutations are random.
>
>
Come on Diana. You keep making this argument but it doesn't make any
sense. Assuming we trust the mutation rates, we can write down the
probability at each generation. What you do with those probabilities is
up to you. But it is indeed useful to know what is likely and what is
not and to have quantitative assessments of those probabilities.
> I have brothers who match 66/67, a father-son who match 66/67, and an
> uncle-nephew who match 65/67. At the other extreme, I have eighth
> cousins matching 111/111 (and 134/136).
>
>
You have an enormous database of people in your projects. Occasionally
you are going to find cases where unlikely things happened. That doesn't
mean the statement that they were unlikely beforehand was incorrect. It
is just that you cherry picked a few coincidences to argue that math
said something was unlikely, yet it happened.

It is very unlikely that anyone will get struck by lightning in their
lifetime. We have enormous amounts of data which show that. Yet people
get struck by lightning and when they do, this statement, while still
true, won't comfort them very much. Yet it doesn't mean that the
statement is wrong or worthless.
> All you can say about your two READING individuals is that they are
> almost certainly related in genealogical time. Beyond that, they
> could connect, literally, anywhere along the line.
>
>
Yes it could be anywhere but some are much more likely than others and
that should be important to know.
Dave




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