In view of the dangers to which children are exposed from the side of the sexual life, the question presses whether and how it is possible to prevent these dangers arising, or, if prevention has failed, to minimise them. To enable us to answer this question, the general question of sexual education will have to be considered. In so far as sexual manifestations in the child may arise from hereditary taint, the sociologist will endeavour to prevent them by hindering marriage or procreation on the part of those likely to give birth to such children (eugenics). Our present knowledge, however, does not enable us to say, when an individual exhibits some particular tendency to sexual aberration, whether this same tendency will appear as a concrete symptom in the descendants. Apart, indeed, from certain cases of very severe taint, we are hardly in a position even to predict with any high degree of probability that the offspring will exhibit morbid endowments. There are marriages which we expect to result in the birth of congenitally defective children, and in spite of this the offspring are healthy; and conversely, we sometimes meet with affections which we are in the habit of regarding as dependent upon hereditary transmission, and yet we fail, in these cases, to find any evidence of such affections in the progenitors. And, apart from these theoretical considerations, the physician's advice is not of much importance, for experience teaches us that in questions of marriage his advice is very rarely followed.