The most damning of Murray’s stats that contradict your position is that of many studies of identical twins, raised by totally different families.
No difference in cognitive ability.
“cognitive ability” is a low level measure.
It does not predict character or values and with character and values comes the different degrees of dedication or sloth, diligence or carelessness, ect., ect., ect., ect. and all the qualities, regardless of “cognitive ability” that help make the individual as successful as possible. Those qualities don’t come with nor are denied by “cognitive ability”. They arise from culture, from the family outward.
The term as “successful as possible” does not pretend everyone can be a “top” whatever. It means rising to the best that is possible for the individual and it requires the individual applying the dedication and diligence to do that.
Median black IQ is 85.
https://en.wikipedia.org/wiki/Minnesota_Transracial_Adoption_Study
130 black infants, adopted as babies by white affluent families with average adopting parent IQ of 120.
The children were raised all their lives by educated white parents, going to middle class schools.
At 17, the median IQ of the black kids was 89.