No doubt general intelligence has a biological hereditary root.  This would probably be directly related to a higher a density of neuron synaptic connections in some people's brains.  On the issue of race well that would probably be more directed to nurture and or culture. For example even amongst whites you will have notable disparities traceable to their environment or socio-economic class (i.e. poor whites vs. wealthy whites). I personally don't believe race is so much as important as culture. Europe ended up conquering the rest of the world during colonial times in a few centuries simply because important social, political and religious changes it underwent mainly thru its secularization or separation of its societies from The Church as a central governing structure vetoing science; and leading to the era of lights and initiating an unrestricted growth of knowledge and the industrial revolution with a huge head start over other parts of the World that remained tied to a fundamentalist Clergy or Authoritarian leaders that didn't see a reason to promote innovation.