I don't know how this ended up in the USMLE but AFAIK, it has long been debunked... unless for "inherited" you mean something other than "genetically transmitted".

See "Not in our Genes" by Lewontin, Rose, Kamin, for a thorough discussion.

In practice, it is a result based on twin studies, but with very low standards: for one thing not double-blind, definitions were let swing arbitrarily by the interviewers, and so on.

Definitions of intelligence are themselves questionable, techniques to measure it, even more so. The history of IQ has been tainted by plain fraud... And the whole field is too a succulent target for ideological warfare... truth is too easily a collateral casualty. This should not be considered science.

This sounds like a myth, as I have never seen such a thing suggested by any expert on the subject.

That's a poor paraphrase of "recent studies suggesting [testable IQ]'s mostly from the mother".

https://books.google.com/books?id=8zVXDwAAQBAJ&pg=PT138&lpg=...