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From:
Subject: Re: [DNA] Genetic Distance calculation -- which method is best
Date: Sat, 22 Nov 2003 11:47:43 EST


In a message dated 11/22/2003 10:30:22 AM Eastern Standard Time,
writes:

> If you have six mutations, with some being more than one step it doesn't
> matter how you count them as the relationship isn't close enough to bother
> with.
>
> Julia
>

Julia:

I have to disagree with this last sentence. Some of us (more and more) are
dealing with Irish or Scottish clan groupings with known or well-estimated
pedigrees of 200 to 1600 years. So, while the relationships may not be close,
they certainly are of genealogical interest. Our purpose is to establish
relationships with various sub-septs which may or may not bear the same surnames.


The formula must accomodate lineages of 1600 or more years which are
involved in these clan groupings.  Also, there may well be different mutation rates
in different lineages, as well as different generation lengths. My average
generation over 51 documented and connected generations is 33.5 years.  Another
study in a similar lineage (McSweeney - also descended from King Niall, 400 AD)
gave an average of 37.5 years, with some good reasons why it is so high.

This means fewer generations than the "normal" of 25 years, with less chance
for mutations, yet we are seeing "too many" (according to present theories),
suggesting non-relationship!  Some groups have tested closer relatives, but I
would hesitate to apply results of other families as there may be definite
family,  ethnic or geographical factors causing differences in mutation rates. 

Len Keane




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