i do not agree with richard. genetics plays a role, but many factors are at play. i have not heard a clear separation of these factors in this discussion. many contradictions. social cultural factors can span generations, and affect many psychosomatic expressions including intelligence. saying that a race is intrinsically inferior to another, is simply wrong and can have tragic effects. we can be clinical about ( it is only statistics). but we know statistics informs public policy and public perception. further, try this exercise  in empathy: you are a young kid in a minority group that has this achievement gap. but you are in the higher percentiles. you become aware of these theories. what is your internal narrative? what sort of pain, and inadequacy you might feel? is that feeling of inferiority conducive at developing in a well functioning, high achieving adult? even if not a minority kid, lacking support and recognition can really stymie development.