Well, you could argue that their understanding of it is implied. Aside from simple heredity, stress during pregnancy and early life could make its mark on the

Well, you could argue that their understanding of it is implied. Aside from simple heredity, stress during pregnancy and early life could make its mark on the child via epigenetics. We know already that this happens in mice-- a young mouse that is touched by its mother receives beneficial epigenetic changes (lower life stress, etc) than mice that are not touched by their mother or not touched a sufficient amount. There are doubtless such mechanisms at play with humans.