Evidence that ethnicity, intelligence and life-chances are linked and largely inherited

It is commonly observed that those of African heritage are less likely to be high-achievers academically and more likely to end up in psychiatric hospitals and prison than the majority white population in both Britain and America. Is this a nurture or nature, or perhaps a combination of both?
Lindblad, F., Hjern, A., & Vinnerljung, B. (2003). Intercountry Adopted Children as Young Adults—‐A Swedish Cohort Study, American Journal of Orthopsychiatry, 73(2), 190-202.

Evidenceethnicity,intelligence