Ellis found that the most frequent age of the father was thirty-two years, but that the average age of the father at the distinguished child's birth was 36.6 years; and that when the fathers were themselves distinguished their age was not, as Vaerting found in Germany, notably low at the birth of their distinguished sons, but higher than the general average, being 37.5 years. He found fifteen distinguished sons of distinguished British fathers, but instead of being nearly always under thirty and usually under twenty-five, as Vaerting found it in Germany, the British distinguished father has only five times been under thirty, and among these only twice under twenty-five. Moreover, precisely the most distinguished of the sons (Francis Bacon and William Pitt) had the oldest fathers, and the least distinguished sons the youngest fathers.
Ellis says of his general conclusions resulting from this investigation: "I made some attempts to ascertain whether different kinds of genius tend to be produced by fathers who were at different periods of life. I refrained from publishing the results as I doubted whether the numbers dealt with were sufficiently large to carry any weight. It may, however, be worth while to record them, as possibly they are significant. I made four classes of men of genius: (1) Men of Religion, (2) Poets, (3) Practical Men, (4) Scientific Men and Sceptics. (It must not, of course, be supposed that in this last group all the scientific men were sceptics, or all the sceptics scientific.) The average age of the fathers at the distinguished son's birth was, in the first group, 35 years; in the second and third group, 37 years; and in the last group, 40 years. (It may be noted, however, that the youngest father of all the history of British genius, aged sixteen, produced Napier, who introduced logarithms.)
"It is difficult not to believe that as regards, at all events, the two most discrepant groups, the first and last, we come upon a significant indication. It is not unreasonable to suppose that in the production of men of religion in whose activity emotion is so potent a factor, the youthful age of the father should prove favorable; while for the production of genius of a more coldly intellectual and analytic type more elderly fathers are demanded. If that should prove to be so, it would become a source of happiness to religious parents to have their children early, while irreligious parents should be advised to delay parentage.
"It is scarcely necessary to remark that the age of the mothers is probably quite as influential as that of the fathers. Concerning the mothers, however, we always have less precise information. My records, so far as they go, agree with Vaerting's for German genius, in indicating that an elderly mother is more likely to produce a child of genius than a very youthful mother. There were only fifteen mothers recorded under twenty-five years of age, while thirteen were over thirty-nine years; the most important age for mothers was twenty-seven.
"On all these points we certainly need controlling evidence from other countries. Thus, before we insist with Vaerting that an elderly mother is a factor in the production of genius, we may recall that even in Germany the mothers of Goethe and Nietzsche were both eighteen at their distinguished son's birth. A rule which permits of such tremendous exceptions scarcely seems to bear the strain of emphasis."
The student, however, must always remember that while the study of genius and exceptionable talent is highly interesting, and even, as is quite probable, not without significance for the general laws of heredity, still we must beware of too hastily drawing conclusions from it to bear on the practical questions of eugenics. Genius is rare—and, in a certain sense, abnormal. Laws meant for application to the general population must be based on a study of the general population. Vaerting, himself, realized how inadequate it was to confine our study to cases of genius.
Another investigator, Marro, an Italian scientist, in his well-known book on puberty which was published several years ago, brought forth some interesting data showing the result of the age of the parents on the moral and intellectual characters of school-children in Northern Italy. He found that children with fathers below twenty-six at their birth showed the maximum of bad conduct and the minimum of good; they also yielded the greatest proportion of children of irregular, troublesome, or lazy character, but not of really perverse children—the latter being equally distributed among fathers of all ages. The largest number of cheerful children belonged to the young fathers, while the children tended to become more melancholy with ascending age of the fathers. Young fathers produced the largest number of intelligent, as well as of troublesome children; but when the very exceptional intelligent children were considered separately, they were found to be more usually the offspring of elderly fathers.
As regarded the mothers, Marro found that the children of young mothers (under twenty-one) are superior, both as regards conduct and intelligence, though the more exceptionally intelligent children tended to belong to more mature mothers. When the parents were both in the same age-groups, the immature and the elderly groups tended to produce more children who were unsatisfactory, both as regards conduct and intelligence—the intermediate group yielding the most satisfactory results of this kind.
Havelock Ellis makes the following plea for further investigations along these lines, in the interest of the well-being of the race: "But we have need of inquiries made on a more wholesale and systematic scale. They are no longer of a merely speculative character. We no longer regard children as the 'gifts of God' flung into our helpless hands; we are beginning to realize that the responsibility is ours to see that they come into the world under the best conditions, and at the moments when their parents are best fitted to produce them. Vaerting proposes that it should be the business of all school authorities to register the ages of the pupils' parents. This is scarcely a provision to which even the most susceptible parent could reasonably object, though there is no cause to make the declaration compulsory where a 'conscientious' objection existed, and in any case the declaration would not be public.