[kss238]

The article discussed this but said that even within family's IQ is going down by generation so it cannot be entirely the effect you described.

[mirimir]

Maybe, even within families, it's higher-IQ siblings who'd rather do non-reproductive stuff.

Edit: Upon reflection, that's rather an ugly way to say it. And in saying that, I was thinking of the well-established fact that reproduction rate is inversely related to educational level and so on.