Page:Popular Science Monthly Volume 59.djvu/223

Rh account, the fertility is greatly pulled down, but still remains well up to the average. This normal average is thus attained by a conjunction of an abnormal proportion of sterile marriages, together with an abnormally high proportion of children among the fertile marriages.

There would appear to be a considerable resemblance between the fertility of genius families and of insane families. We have seen previously that our eminent British persons belonged to families of probably more than average fertility; we now see that they themselves produced families of probably not more than average size, owing to a greater prevalence of sterility. In France, Ball and Régis, confirmed by Marandon de Montyel, appear to have found reason for a similar conclusion regarding the insane. They state that natality is greater among the ascendants of the insane than in normal families, but afterwards it is the same as in normal families, while they also note the prevalence of sterility in the families of the insane. The question, however, needs further investigation.

With regard to the distribution of families of different sizes, the results, as compared with the figures already given, are as follows:

Allowing for certain irregularities due to the insufficient number of cases, the interesting point that emerges is the return towards the proportions that prevail in normal families; it will be seen that in all but a few cases the families of men of genius differ from genius-producing families by approximating to normal families. It must be remembered that in neither of our groups are the data absolutely perfect, but as they stand they confirm the conclusion already suggested that men of genius belong to families in which there is a high birthrate, a flaring up of procreative activity, which in the men of genius themselves subsides towards normal proportions. The slightly larger average size of the families of men of genius as compared with normal families is merely due to the presence of a few families of excessively large size.