When I read it 16 years ago, I went to the length of actually looking up some of the twin studies. My impression is that they are not as compelling as it sounds

When I read it 16 years ago, I went to the length of actually looking up some of the twin studies. My impression is that they are not as compelling as it sounds. For example one study had 40 individuals, but they were not a homogenic group. It's not that you have 40 twins seperated at age 4 and then tested at age 40. It's actually very rare for twins to be separated and therefore the stories are usually complicated. Some things in the papers made actually doubt them more. For example they mentioned one pair who they found wearing the same clothes and having given their kid the same name. I'm sorry, but there is no gene for tastes in clothes, at least not to that degree. Neither is there a gene for picking kids names. So those studies certainly overshot in some aspects. In the actual IQ data there was also quite some variation.