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Archiver > GEN-MEDIEVAL > 1996-02 > 0823196445


From: Chris Bennett <>
Subject: Adultery (Was: Royal lines)
Date: Thu, 1 Feb 1996 09:40:45 PST


Subject: Re: Royal lines
Author:
Date: 1/31/96 3:21 PM

I may be throwing a match on a puddle of gasoline here, but I regard any
pedigree claiming descent from Adam or the House of David as totally
worthless.

<snip>

________________________________________________________________________

I guess you get to be an old-timer in this group when you recognise a
recurrent theme. Last time this one came around we had a debate on the
relative values of oral tradition vs written evidence and on the
cultural significance of mythical genealogies. It looks like we may be
about to head back down this road.

With apologies to the original poster, I'd like to hijack this
discussion into a different direction. Here is a little bomb for pyros.

Any assertion of paternity, even if perfectly documented, is only an
assertion unless supported by biological proof. Jared Diamond, in
p85ff of his book on human biology "The Third Chimpanzee" (New York,
1992) reports a 1940s study on the blood types of new born infants
which, embarassingly, revealed that nearly 10% of American children
were conceived adulterously. He reports that other similar studies in
both the US and Britain have shown numbers of 5-10%.

The implications of these observations for patrilineal genealogical
research over large numbers of generations are nothing short of
devastating.

Consider the following simple probability analysis using Diamond's
female adultery rate of 10%. Suppose an average intergenerational
interval of 25 years, i.e. four generations a century. Then, the
probability that a perfectly documented patrilineal descent refects
actual events (i.e. no conceptions in female adulteries) is 0.9^4n,
where n is the number of centuries in the descent. (If you want to
generalise, use this formula to calculate probabilities over the
numbver of male-line generations in a descent.) This goes roughly as
follows:

Number of centuries Probability of no adulteries

1 0.66
2 0.43
4 0.19
8 0.03

In other words, a patrilineal descent, no matter how well documented,
has no more than 43% chance of being accurate after a mere two
centuries (8 generations). By the year 1200, its absolutely and
totally worthless.

One may argue that our distant maternal ancestors were less inclined to
(or, depending on your view of human nature, had fewer opportunities
for, and/or took greater risks with) adultery than American women of
the 1940s. For the sake of this argument, let's suppose that the
historical average probability that a child was conceived adulterously
is only 1% instead of up to 10%. Then, the probability that a
perfectly documented patrilineal descent refects actual events is
0.99^4n. This goes roughly as follows:

Number of centuries Probability of no adulteries

1 0.96
2 0.92
4 0.85
8 0.72
16 0.53

In this case, in other words, even if you had unimpeachable
documentation that took your paternal line back to the start of the
Dark Ages (let alone to Adam!) there is still a 47% chance that you
have at least one undetected adultery on the way which renders your
line in error.

The documentation is not only highly impeachable, but on this subject
is at times wilfully ignored. A classic example is Catherine II of
Russia, whose memoirs explicitly state that her son, the future Tsar
Paul, was the son of a lover, not of her husband Peter III -- yet
virtually all royal genealogies show Peter as Paul's father without
question. At times, the issue is central to a descent that affects
many people. For example, the best argument I know for a traceable
descent from antiquity depends critically on the 9th century Byzantine
empress Eudocia Ingerina having been an adulteress.

Those who seek to build long genealogies need to face up to this issue
and decide how they want to integrate it into their research. It seems
to me that anyone who craves absolute certainty had better focus on
documenting matrilineal descents rather than patrilineal ones. Or
else, they should be prepared to do a lot of grave robbing and DNA
analysis!

Chris

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