This also leads me to consider another generality which is frequently used as an argument by those who oppose conscious and deliberate parenthood. Some people say that by the direct control of the size of the family to a small limited number which the parents definitely desire, we would be eliminating genius from our midst, and their argument runs: Look at Nelson, he was a fifth son; look at Sir Walter Scott, he was a third son; and so on. This to the uncritical seems conclusive, and many people of great capacity, ideals and heart, who otherwise would be wholly on my side in my claim that every child born shall be deliberately desired, and that all other conceptions shall be consciously prevented, are swayed by this argument and say: “Yes, your position would be obviously the right one for the race if it were not that later children are so often the better.” I turn, therefore, to a consideration of the life histories of these men’s mothers. Why was Nelson the genius of his family? Because his mother was too young to bear geniuses at the time she was bearing her elder children. But this is not yet a sufficiently accurate consideration of the subject; I want to know also of which type the mother was, for, in my opinion, the right age for the parenthood of a woman depends also on the type to which she belongs, whether the early maturing or the late maturing. If she knows herself to be the latter, after it is patent, as it must become patent to every one once the idea is placed before them, that such women are in our midst, then that woman and her husband should usually defer parenthood until she has reached at least thirty years of age. If this were done, then not the fourth, fifth or seventh but the first child would stand a very great chance of being a world leader, a powerful mind, perhaps even a genius. First children have been geniuses (Sir Isaac Newton was an only child); all depends on the age, the conscious desire, the general type and the surrounding conditions during prenatal state of her infant, of the mother who bears him and the father from whom he also inherits potentialities. A few investigations bearing on the effect of the parent’s age have been published by the Eugenics Society and some individuals, but none of these appear to me to be of any value, for none take into account the necessary data concerning the type of the mother which I here point out, and in all the calculations crude errors occur.