How do cattle-breeders improve their stock? By breeding from the best animals, and not from the worst.
Men of weak or base moral natures, and men of weak minds and bodies will, I believe, generally reproduce their faults in their descendants. But, to marry, they must find wives.
I said a little way back, "take care of your women, and the race will take care of itself."
Good environment would "take care of the women." The women being properly nursed, fed, taught, and honoured, would select partners who would not shock them morally, nor disgust them physically.
Virtuous, refined, and intelligent women do not, in general—there are exceptions—love and marry men of weak minds, nor men of diseased bodies, nor men of low moral type.
Therefore, given proper environment, the "born criminal" and the mental weakling would not be able to find wives. But that is not the only way in which good environment would affect the breed. Nearly all degeneration is caused by bad environment, and good environment would stop degeneration, and by that means would improve the mental, moral, and physical average.
It has been suggested, by some of the most dismal scientists, that to prevent the spread of degeneration we should prevent degenerates from marrying. But I think a sounder method would be to stop the production of degenerates, by abolishing the environment that produces them.
As to the atavist, or "born criminal," I would point out that one of the laws of heredity is the tendency to "revert to the normal." That is to say, genius and atavism do not "persist." In a few generations the atavist and the genius have bred back to the average level.
That, as I have pointed out, is due to the mixture of blood by marriage.
Thanks to this law, even the "born criminal" cannot often reappear. An example of the working of this law is afforded by the descendants of the Australian convicts, who have turned out excellent men and women.