How much of your IQ actually comes from your genes and how much comes from how you were raised?
I know this is a loaded topic but I want to understand what the actual data says, not the political version of it. Twin studies get cited a lot but I also hear that they have serious methodological problems. Adoption studies seem more convincing to me but I never see them discussed as much. What is the current scientific consensus on heritability of intelligence and how confident should we actually be in those estimates?
The consensus among researchers who actually study this is that genetic influences on intelligence are substantial and well replicated across multiple methodologies. Twin studies consistently find heritability estimates in the range of 50 to 80 percent in adulthood, with the higher end applying to older adults. Adoption studies largely converge on similar conclusions. Children adopted into wealthy families show IQ boosts in childhood that largely fade by adolescence, at which point their scores correlate more strongly with their biological parents than their adoptive ones. That fadeout pattern is one of the cleaner pieces of evidence because it controls for shared environment almost by design.
The adoption fadeout finding is the one that tends to shift peoples priors more than anything else. If shared family environment were the dominant force you would expect adoptees to resemble their adoptive parents more over time, not less. The fact that the opposite happens is hard to explain without substantial genetic influence.