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From: Stephen Hayes
To: All
Date: 2002-12-30 13:14:32
Subject: Ancestors Double with Each Generation

* Forwarded (from: GEN_BRITAIN) by Stephen Hayes using timEd/2 1.10.y2k.
* Originally from Graham Coward (8:8/2002) to Graham Coward.
* Original dated: Sun Dec 29, 00:46

From: "Graham Coward" <coward{at}>

Does anyone know where the following dissertation came from? It makes sense
to me. What do others think?

Graham Coward
(who remembers when telephones used cables and television didn't)

In theory the number of ancestors doubles at each generation however, in
practice, the number does not keep doubling, because two separate lines of
descent will sooner or later converge to people who are cousins, then
siblings, and then to a parental couple common to both lines.

For many families, the number of generations from 1975 to the (Norman)
Conquest is 27, so the number of theoretical ancestors in the generation of
1066 would be 41,508,864: but the whole population of England at that time
is reckoned to have been about 1,250,000 made up of three generations -
grandparents, parents and children.  The middle, parental generation will
then have been about 600,000 persons or 300,000 couples.  It is reasonable
to assume that the descent of at least half of those will have died out at
various times during the last 900 years, so surviving lines will lead back
to about 150,000 couples.  If these pairs have to embrace all of the
41,508,864 theoretical ancestors of each of us who is of English descent, it
seems statistically inevitable that all the 150,000 couples are our
ancestors, and that includes William the Conqueror and his queen.
Admittedly Scottish ancestors and foreigners will effect the figures to some
extent, but the extent of compression of a constantly doubling number of
theoretical ancestors into a constantly "contracting" population,
seems more
than enough to outweigh the effects of "alien" lines.

The above conclusions have been objected to on the grounds of exclusive
class divisions and the static position of families in remote valleys, but
this alleged difficulty seems to overlook the fact that class divisions have
never been absolute in England, that family immobility is largely irrelevant
when all the female descents are included, since only a minority of brides
and bridegrooms have been "both of this parish' and only one bride from
outside the valley is needed to break the segregation of descent.

Author unknown.

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