SIR - I respond to Ulrich Mueller's
comment on social status and sex (ratio of
offspring), based on an examination of
biographical compilations2. The authors
are presumably interested in the biologic-
al phenomenon of sex ratio at (live) birth.
The representation of children in compila-
tions such as Who's Who is a socially
stressed report that is subject to a variety
of distortions: reporting of perinatal mor-
tality, illegitimacy, children of plural mar-
riages, adoption and repudiation: all these
are likely to be biased by social class and
by sex. The data given can hardly be
accepted at face value. If they were to be,
we would then have to remove confound-
ing with variables such as parity and age of
mother, as well as differential prenatal
mortality that may be associated with
infection, malnutrition and other socially
correlated causes.

Unfortunately, it is difficult to find large
datasets organized by biological family
relationship. The large population census
datasets are acquired by household rather
than family, and are beset with many
errors in statistical detail'*.
Joshua Lederberg
The Rockefeller University,
1230 YorkAvenue,
New York, New York 10021-6399, USA

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33%-374U986).

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9. James, W. H. Hum. Biol. 59,873-900 (i987).'
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  GeneticDemography, Proc. III Int. Congressof Human
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