From John Goodman’s Health Policy Blog:
A recent paper in Molecular Psychiatry … confirms that genes account for about half of the difference in IQ between any two people in a modern society, but that the relevant genes are very numerous and the effect of each is very small. The genes for intelligence are there, but there are thousands of them and each has only a tiny impact. So the old terror, which so alarmed many psychologists and educationalists, that one day people — or governments — would use genes to decide whom to kill, sterilize or prevent being born because of their intelligence, suddenly looks a lot less scary. There are just too many genes.
Entire Wall Street Journal article on IQ here.
While I’m not a geneticist, I would imagine that as with IQ so too with any number of complex human traits and behavior. The matter is simply too complex to identify a single gene–or even a small collection of genes–as the cause of this or that behavior or trait.
Addendum: John Cleese talking about genetics….