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From: "Belinda Dettmann" <>
Subject: Re: [DNA] "NW Irish" vs. "Ui Neill" - the gap in time
Date: Sun, 12 Mar 2006 14:16:20 +1100
References: <23b.8700d8f.3144df71@aol.com> <000a01c6457d$ae4ba760$bec79045@Ken1>


Ken wrote:
> When I first joined the list I used 25 years for a generation. Most of
> the other regulars on the list insisted on 30 years or longer. Maybe one
> of them will submit the evidence again for your benefit.

My family's longest line goes back to Cerdic and it has one doubtful link,
but it's useful for calculating the average generation interval. This
pedigree covers 1507 years over 50 generations, for an average of 30.14
years per generation. I can get an independant estimate from my direct
maternal line, traceable for 10 generations over a span of 297 years, which
averages 29.7 years per generation. Lines are Anglo-Scottish apart from the
last 4 generations, and 30 years appears to be about right.

I still use 25 years as my first estimate when ancestor-hunting as it is
useful for fiding the first child of a marriage. But the average generation
time is analogous, in some sense, to the middle child of each generation.
As family size can be very large, often spanning 20 years or so, this is
still a useful measure. But it isn't the average generation interval.

Belinda in Australia



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