and is traceable through three generations, though it sometimes skips a generation. In one family of three hundred and nineteen persons, one hundred and nineteen were known to be feeble-minded, and only forty-two known to be normal. The families tended to be large, sometimes very large, most of them in many cases dying in infancy or growing up weak-minded.
Not only is feeble-mindedness inherited, and to a much greater degree than has hitherto been suspected even by expert authorities, but the feeble-minded thus tend (though, as Davenport and Weeks have found, not invariably) to have a larger number of children than normal people.
That indeed, we might expect, apart altogether from the question of any innate fertility. The feeble-minded have no forethought and no self-restraint. They are not adequately capable of resisting their own impulses or the solicitations of others, and they are unable to understand adequately the motives which guide the conduct of ordinary people.