There are likely many hundreds or more of contributing alleles according to one paper I read in uni. How individual differences manifest genetically is stultifyingly complex. We still don’t even have a unifying theory of what intelligence is, or even consciousness - much less “how make smarterer”. It’s before early days, we’re still banging rocks together. Scientists know approximately dick about intelligence.
That’s the really crazy thing, innit? We don’t even know what being conscious entails! But we’ve got over one hundred years of studying (“studying”) psychology while just handwaving the underlying mechanisms. We have no idea how all the genes interact, much less how environment directly influences all of that, but we’re still trying to do complex eugenics that’s lightyears past our current understanding.
Maybe we get to Gattaca someday, but it’s not going to be soon.
