It's gonna take me a bit to figure out how to use the website for NLSY79 so bear with me on that.
The youngest of the cohort in 1979 was 14, since segregation was only officially ended in 1965, it once again seems more likely the legacy of segregation and America's continued racist culture had a larger impact on outcomes than IQ test scores to me.
But, I'm a biologist not a sociologist, so not really my field of expertise.
Edit: the National Longitudinal Study of Youth doesn't even test for IQ, this has been a waste of time.