[Footnote 64: Barr, op. cit., p. 94.]

[Footnote 65: Ibid., p. 109.]

Dr. Arthur Mitchell examined all idiots in nine counties of Scotland
and found that 42 out of 519 or 8.1 per cent of whom the parentage was
known, were children of first cousins.[66] Dr. Down found 46 out of
852 or 5.4 per cent to be children of first cousins.[67] Dr. Grabham
of the Earlswood Idiot Asylum in Surrey, England, stated that 53 out
of 1388 patients were the offspring of first cousins. The facts, he
adds, were obtained from the parents and are "therefore tolerably
trustworthy."[68] Other investigations give percentages as follows:
Kerlin, 7; Rogers, 3.6; Brown, 3.5 and C.T. Wilbur, 0.3.[69]

[Footnote 66: Darwin, see _Jour. Stat. Soc._, p. 173.]

[Footnote 67: Huth, _Marriage of Near Kin_, pp. 210-211.]

[Footnote 68: Darwin, op. cit., p. 166.]

[Footnote 69: Barr, op. cit., p. 109.]

The earlier American writers, Drs. Howe and Bemiss, believed that
consanguinity was a cause of idiocy. Dr. Howe inquired into the
parentage of 359 idiots and found that in 17 families the parents were
nearly related; in one of these cases there were 5 idiotic children;
in 5 families there were 4 idiots each; in 3 families 3 each; in 2
families 2 each; and in 6 families i each. In all 17 families there
were 95 children of whom 44 were idiots, 12 were scrofulous and puny,