Ok this is a weird question I have been ruminating on for some time, but I have no real expertise in genetics at all. All my reading suggests that IQ is highly genetic (the potential, not the achievement). That people marry within 10 points, siblings are usually within 10 points of each other and that our friends tend to be in the ball park. That all makes sense to me.
My question is - is the incidence of high IQ children (and possibly other neurologically interesting children) increasing in recent generations because the gifted are more likely to find and marry each other now than ever before?
I agree that "assortative mating" based on education has risen while that based on less-IQ-loaded factors such as religion has declined. An opposing effect leading to fewer gifted children is that IQ is negatively correlated with fertility. For example, the fertility of college educated women in the U.S. is about 1.6, below the replacement level of 2.1. The Wikipedia article "Fertility and intelligence"
http://en.wikipedia.org/wiki/Fertility_and_intelligence has research on this. Worry about the dysgenic effect of a negative correlation between IQ and fertility caused me to write in another thread
http://giftedissues.davidsongifted....ase_for_Having_More_Kids_.html#Post98909 , devoted to Bryan Caplan's book "Selfish Reasons to Have More Kids", that "[since] intelligence is highly heritable, it is especially important for smart people to have lots of children."
I read the Bell Curve before I was dating, and wanting smart children -- in addition to wanting intelligent company -- caused me to filter based on education and profession. I decided to have a relatively large family (three children) partly because of the social concern mentioned above. It seems to have worked -- my eldest son is highly gifted, and the second may be moderately so. I also enjoy my children.
