Sowell talks about Cultural Capital as being foundational to intelligence and success.
However there are dull children as well as bright ones even in the early years.
Employers and schools are not allowed to treat members of protected minorities as individuals.
The government currently asserts that any disparity in results which negatively affects protected minorities, is evidence of discrimination, which MUST be remedied through affirmative action and other measures, or the "discriminating" entity will face legal consequences.
On the subject of "Cultural Capital", a few decades ago the Minnesota Transracial Adoption Study looked at children with black biological parents who were adopted into affluent white families. The kids grew up in middle class white culture, went to good middle-class schools, had all the advantages of white kids, since babyhood.
IQ tests administered at 17 showed the black kids with an average IQ of 89.