Ebonics is a slang (and on the verge of derogatory) term for the dialect of generally the lower income black population of urban areas. Notice I said "generally". This is a stereotypical term, and therefore cannot be used as an absolute to describe a multitude of people.

This dialect is not necessarily a sign of lack of education; people can choose how they speak. I agree that dialects are spread culturally, but they are not transmitted genetically. Also, this dialect is not derived from African dialects; it is derived from the South. The first members of the black population of the United States were brought to the country as slaves or workers, and they were almost exclusively enslaved in the South.

I would like to add that I am not black (in case somebody thinks I'm trying to start a race riot.