Heritability of traits can be measured by twin studies. Some people have spent quite a lot of time doing this for IQ. Others have even identified some of the genes that are correlated with high IQ, TOR1A being one of the more interesting ones. I'd be interested to hear your thoughts on this area of research.
Regarding population genetics, I don't think it matters as much as people seem to think. Han Chinese are short, but Yao Ming is tall, and there's no contradiction in that.
Regarding Urbit, I certainly hope that it isn't heritable, or for that matter infectious, because it seems totally opaque.
>"Heritability of traits can be measured by twin studies."
No, correlations between traits can be measured in twin studies, but they do not prove a causal link.
In the realm of intelligence, it could be (and I would argue) that looking like a nerd generally proceeds becoming one. People become social outcasts, and then become intelligent as a defense mechanism. That is,once in that nerd social caste, a greater percentage of people will find themselves using their brains more often. As a result, they get smarter, and score better on IQ tests.
Because twins are liable to look the same way, have the same temperament, same physique, etc. they are liable to be pushed into the same sorts of social groups, and as a result the same sorts of interests, ultimately pushing their IQs up or down together.
This would not mean that IQ is heritable, but that traits which can have a forcing effect on nurture (and thus IQ) are heritable.
How about torsion dystonia? Increased IQ can be observed before the onset of the disease, even when matched to comparable members of the same population.
One, Torsion Dystonia could just as easily be effecting something else which effects IQ.
Two, the studies on Torsion Dystonia decided to only study people who were not showing symptoms. This means they were selecting around heredity, since those who show symptoms and those who don't were not divided on gene expression -- there is only one allele in play as far as we know.
Three, the study was 14 persons. Removing a single person from the sample could have swung the data to say the opposite.
Yao Ming was potentially part of a breeding program, of a sort. This is an argument that population genetics does matter, in that you generally get whatever the past has selected for unless you make a deliberate effort otherwise. Otherwise it's a no show.
Regarding population genetics, I don't think it matters as much as people seem to think. Han Chinese are short, but Yao Ming is tall, and there's no contradiction in that.
Regarding Urbit, I certainly hope that it isn't heritable, or for that matter infectious, because it seems totally opaque.