-----------------------------------------------------
3. Epileptic Insanity | 5.6 | 4.9 | .64
Hereditary | 11.7 | 9.9 | 1.57
Not hereditary | 3.5 | 3.2 | .29
-----------------------------------------------------
4. Idiocy and Imbecility| 14.4 | 12.8 | 1.58
Hereditary | 21.6 | 19.3 | 2.12
Not hereditary | 11.5 | 10.2 | 1.37
-----------------------------------------------------
[A] Per thousand.

[Footnote 73: Feer, op. cit., pp. 13-14.]

From these tables we may infer that consanguinity influences idiocy
far more than it does insanity, but it is not entirely clear why the
number of hereditary cases should be relatively smaller among the
idiotic. Since insanity is more likely to have some more definitely
assignable cause than idiocy, we should expect the percentage due to
heredity to be lower and consequently the influence of consanguinity
less.

It is generally admitted that a tendency toward insanity is
inheritable, and it seems probable that this tendency as well as other
neuroses may be intensified through double heredity. A case in point
can be found in the Shattuck genealogy.[74] For four generations in
the S. family there is no indication of neurosis. The average number
of children to a family had been eight, few children died young and
all were prosperous farmers. But in 1719 J.S. married E.C. and their
son Z.S. is thus described: "He was sometimes subject to depression of
spirits; and some peculiar traits of character in a few branches of