My mother is from Kansas,

So he's only half black.

And when you say black, you mean 100% Africans.

Black people also include Sudan and Bantu. Their distribution in Africa is roughly bounded by the equator. Sudanese people live in the north of the equator and are characterized by pure black skin color; Bantu people live south of the equator and are characterized by light black skin color.

They may be Sudanese, which is why they are so dark.