…….I have not yet studied Murray’s claims in detail, but it sounds like he is reporting the results of his studies and positing a hypothesis to account for those differences. He may be dead wrong, but nonetheless, this sounds like a case of the Left shooting the messenger of information that they do not want.
FWIW, my anecdotal experience tells me that both nurture and nature have bearing. Smart parents have smart kids. And kids from happy, intact nuclear families produce better students. But the thing is that I have seen examples of that in all three major races (though not at the same rate when it comes to the family stability).
I would be inclined to disagree with Murray on the nature aspect of his claims, but I see open dialogue for scientific discussion as valuable.