[jp57]

One point he doesn't bring up is that this could be an evolutionary selection event. As wealth, education, birth control, and abortion make it possible for women to choose whether or not to have children many are choosing to have zero or one child. But some are not. I know a handful of well off, educated women with more than two kids.

If those tendencies are based on heritable personality (or other) traits and not purely random or situational, they would be selected for in the current environment. Not sure how we'd determine if they are.

[necovek]

There are so many societal and environmental confounding factors, that I don't see how I would ever trust a study that would claim this.

What we are learning so far is that genes tell an extremely complex and probabilistic story.

There is no way we have "evolved" through selection in many countries from 4+ kids to <2 kids per mother in a span of a 100 years, so while we could possibly see such a genetic effect over thousands (probably more) of years, there is no way we could see it in the span of a century.

[Dig1t]

Yes! I completely agree. It seems likely to me that the desire to have kids has at lease some genetic component. If most people with a weaker drive choose to not have kids then the ones who are left, those with a stronger drive, will pass their propensity on and the overall population will have a stronger drive to procreate.

I don’t know how many generations it would take, but ultimately it is a problem that might solve itself.