Comment by simonh

Race is a combination of genetic, and cultural factors such as nutrition, early childhood care practices, social values, etc.

Humans are far more genetically homogenous than many animal species due to a population collapse at one point in our developmental history.

Cultural practices can have a big effect on intellectual development, so disentangling any possible genetic factors from cultural ones can be very difficult, but there is very little evidence for genetic factors related to race also being related to intelligence at the population level. Obviously certain genetic disorders can have a significant effect.