[morog]

genuine question - what do you mean by smart people? High IQ? Deep knowledge about mankind's place in the Universe / natural order? or their ability to maximise their own personal happiness over their lifetime? If the last point, then personal experience would suggest that having kids makes you happier person (once they are sleeping through the night)YMMV

[taneq]

Probably a high 'g factor' ( https://en.wikipedia.org/wiki/G_factor_(psychometrics) ).

[toasterlovin]

High IQ.

[seedie]

The criticisms section in the Fertility and intelligence article on Wikipedia is interesting https://en.m.wikipedia.org/wiki/Fertility_and_intelligence#C...