Among the conditions of parents which are capable of influencing the characteristics of children must be included the changes which their organism undergoes by reason of advancing age.
I propose to study the effects of age on the physical and moral characters of the children. My researches have extended to numerous criminals and insane persons, as well as to scholars of the public schools and other normal persons affected or not with special diseases.
Of my studies on criminals, the result is: that the children of young parents are found in large numbers guilty of offences against property; and this is natural. The first impulse to that is not due to wickedness, which impels them to inflict harm on others, but to love of pleasure, of revel, of idleness—all features of youth, during which period the passions are very active, and no restraint present with which to repress and subjugate them.
Swindlers alone are exceptions to this rule, but swindling is a crime of riper years, according to the dictum of Quetelet.
Among crimes of personal violence, I have found a numerical superiority in the children of aged parents. Assassins, homicides, those who show the completest absence of sentiments of affection and often delusions of persecution more or less pronounced, gave a proportion of children of aged parents far greater than that furnished by all the other categories of delinquents; the proportion is as high for fathers as for mothers of advanced age.
Here, too, we note a certain correlation between the state of discontent, of suspicion, of frigid egoism, which the decline of physical energy tends to arouse in the old, and the absence of affectionate sentiment and a tendency to delusions of persecution which are usual in murderers. Among the insane, moral idiocy in particular, and the degenerative forms in general, appeared more frequently in children of aged parents.
As to schoolboys, I have noticed that the minimum of good conduct and the maximum of better developed intelligence coincides with the possession of youth by both parents.
The age of complete development corresponds to a maximum of good conduct and a minimum of bad conduct, and retains a large proportion of intelligent children.
In the period of decline of both parents, good conduct of children is observed in a smaller proportion than in the preceding period, and high intelligence in a very small proportion.
Among biological qualities I have made observations on longevity; among persons of 70 and 80 whom I have examined there is a large proportion of parents who themselves enjoyed remarkably long lives, which proves the transmissibility from father to son of powers of resistance against the stresses of life.