If it be true that the best stock, both male and female, for various reasons refuses to assume the duty of reproduction, the group will necessarily be replaced from individuals of average and inferior (but not superior) eugenic value. Even within these limits there is at present no conscious eugenic selection, and the irrational and unconscious motives which govern sexual selection at the present time may induce the choice of a mate from among the weaker individuals. Once again it becomes a matter of chance whether or not the matings prove to be for the welfare of the group and of the race. It might be contended that the very fact that certain individuals withdraw from reproductive activities is sufficient proof of their lack of normal emotional reactions adapting them to the performance of those functions. But a clearer insight shows that the group standards permit the exercise of the reproductive activities only in accord with arbitrary regulations which have coalesced in the institutions of marriage and the family. These institutions have been developed to fit a definite ideal of manhood and womanhood which grew up out of a manner of thinking in accord with taboo control and ignorant superstitions rather than in harmony with the actual facts of the situation. Now that we are facing reality and trying to rationalize our thinking, we find that the variation from these masculine and feminine ideals does not necessarily imply biological or psychological abnormality, since the ideals were themselves established without reference to biological and psychological data. The traditional marriage and family arrangement tends to enforce a selection of individuals who conform most nearly to these artificial types as parents for the succeeding generations. It is not at all certain that such a selection is advantageous to the group. It would seem rather that in so complex a social system as that of the present day with its increasing division of labour on other than purely sexual distinctions, we need a variety of types of individuals adapted to the varied activities of modern life.