What if skull shape determines a person's personality? It would be best if your hypothetical scenario was something with more than a shred of long discredited science behind it.

Are you aware of a discussion of the best scientific research and arguments on either side? my understanding is the same as yours but I’d like to become more educated on the topic

Basically the only academic work since the decline of eugenics that has tried to make this case is the bell curve by Charles Murray. It attempted to prove that the differences in IQ between races are genetic, but it's methodology was not up to the standards you would want for such a provocative claim.

This video goes over a lot of the problems with the book.

https://youtu.be/UBc7qBS1Ujo

https://youtu.be/UBc7qBS1Ujo

Not at all. There's a lot of research into the causes of black/white inequality and IQ differences. It's nowhere near as conclusive as you suggest. This is not phrenology so your comparison to that is an unproductive straw-man.

Where's the evidence that there is no significant inherent biological such as genetics? Just because it's a popular belief doesn't mean it's strongly supported by evidence. I haven't seen any. I even saw an adoption study that attempted to answer that, and when it embarrassingly turned out that black kids still had lower IQs despite their white adopted families, the authors suddenly discovered they'd forgotten to control for age at adoption and that must surely have been the cause of the differences. They were silent on the effect of the race of the biological parents even though it could be clearly seen in the data that the more black biological parents a child had, the lower his IQ despite the race and income of his adopted parents.