If one considers studies from around the world, across many cultures, it's pretty clear to me that there's no IQ huge disadvantage to having African genetics. Nigerian immigrants are presently kicking ass and even outdoing Asians. Immigrant from many Caribbean backgrounds do very well. Also cited by myself elsewhere, there's a study that found that the African American children of US servicepeople in Germany was basically the same as their classmates. Whatever's the cause of lowered IQs in underprivileged African American children in the US, it's not genetic.

Historical IQ studies suggest that immigrant groups can raise their average IQs by a lot. Historical studies of such groups also indicate that the degree of group assimilation and participation in society versus group isolation can have huge effects on the wealth of the group. A pattern that arises again and again, are elites of some such groups that keep their group isolated to retain subgroup power. This pattern can cause the same ethnic group to have widely disparate economic success in different parts of the world. (German immigrant communities are a good example of this phenomenon.)

The above is discussed in Thomas Sowell's Migrations and Cultures.