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[A] Eight cases of doubtful fertility.

[Footnote 45: Op. cit., p. 181.]

It will readily be seen that the conclusion is negative, since the
variation is slight, but the higher fertility of the cousin marriages
is interesting.

On the other hand de Lapouge quotes a case of a community founded two
centuries ago by four families and populated almost entirely by their
descendants, in which from 1862 to 1886 there were 273 marriages of
which 63 were consanguineous and 26 were between first cousins. Among
the non-consanguineous 3 per cent were uniparous, as against 7.95 per
cent among the consanguineous. 7.5 per cent of the non-consanguineous
were sterile as against 16 per cent of the consanguineous.[46] The
importance of these percentages is impaired by the fact that they
involve only five uniparous families and ten sterile ones, and that of
these latter only five were sprung from first cousins.

[Footnote 46: De Lapouge, _Les Selections Societies_, p. 196.]

It is almost impossible to get any accurate statistics of sterility
from genealogies, for when no children are given in the record, there
is always a strong possibility that there were children of whom the
genealogist has no record. However, of 16 first-cousin marriages of
which the record expressly stated "no issue," or where it was
practically certain that no issue was possible, the average age of the
brides was 34.3 years and that of the grooms was 39 years, showing
that consanguinity could not have been the only cause of their