Page:Popular Science Monthly Volume 58.djvu/607

Rh be abnormally large. In genius-producing families there is an invariable deficiency of families below the average normal size, and an invariable excess of families above that size. In the largest size group (over 14) the excess becomes extravagantly large; this, however, may be partly accounted for; we may be sure that the biographers have seldom failed to record families of this size, so this group has really been recruited from the families of all our 902 eminent persons. Even on this basis, however, it remains extremely large; in Denmark, for instance, it is stated, a family of 22 children only occurs once in 34,000 marriages.

If, as seems probable, it may be asserted that genius-producing families are characterized by a tendency to an abnormally high birth-rate, this is not a fact to cause surprise. It might, indeed, have been anticipated. The mentally abnormal classes generally belong to families with a high birth-rate. This has been shown by Ball and Regis (confirmed by Marandon de Montyel) to be markedly the case as regards the insane. Magri has found it to be the case as regards criminals, as well as regards the epileptic, hysterical and neurasthenic.

An interesting point, and one which can scarcely be affected at all by any twist in the biographical mind, is the fact that our men of ability (the women are here excluded) are the offspring of predominantly boy-producing parents. Taking the 64 families in which the number of boys and girls in the family is clearly stated, and excluding 12 of these as consisting only of boys, we find that there are about 6 boys to 5 girls, or more exactly, 111 boys to 100 girls. The normal proportion of the sexes at birth at the present time in England is about 104 boys to 100 girls. It is in accordance with the predominantly boy-producing tendency of families yielding men of genius that the families yielding women of genius should show a predominantly girl-producing tendency. Here, indeed, our cases are far too few to prove much, but the results are definite enough so far as they go. Putting aside the families consisting only of girls, the sexual ratio is rather more than 3 boys to 4 girls, or more exactly, in the ratio of 85 boys to 100 girls. Putting the matter in another way, we may say that, while in every ten families from which men of genius spring, the boys