l as of the mother, influence the physical well-being of the
developing child, and thereby affect its emotional stability and other
qualities. Until this question is scientifically settled it is obvious
that the men best fitted for marriage and parenthood are those who act
in such a way that they cannot harm their children no matter which view
is correct.

Let us return once more to the problem of deciding how far the mental
and social characteristics of ourselves and of the persons we are
interested in are due to inheritance and how far to pre-natal and
postnatal environment. In the present state of knowledge no exact
decision is possible. Nevertheless, in some families an undesirable
trait is exhibited by a parent, brothers or sisters, and perhaps by more
distant relatives. In such cases, it is probably inherited, or at least
due to an inherited deficiency or tendency of some sort, and there is a
chance that it may be handed down to the next generation. On the other
hand, many persons who suffer from some form of emotional instability
come from families in which the parents and near relatives appear normal
in this respect. In such cases it is probable that the trait is not
hereditary, but due to some influence in pre-natal life or childhood.
Until the sciences of human genetics and eugenics have made more
progress, the safest way to judge in such matters is by the qualities of
a family as a whole.

Whether you have any doubt about this or not, a thorough examination by
a good physician who is also a psychiatrist and a man of fine character
will be a great help. The physician must frame his judgments for the
good not only of the individual who consults him, but of the prospective
partner, and of the children who may be born to such a couple. Even the
best physician is often unable to decide whether a given defect is
hereditary. He can merely frame an opinion based on the _whole family_.
Young people find it hard to believe that they marry into families, but
they do. As the old Jewish saying puts it, "It is not good to marry a
maid who is the only good maid in her family." The responsibility that
thus rests on physicians is tremendous. That of the young people who
wish to be married is also great, but very different. Theirs is to
submit themselves fully and frankly to the physician's examination and
advice. He may decide that it is safe to marry a person of stable
temperament, but not one who is nervously unstable.