That is an interesting and important topic. It does seem to me that this article makes the case for systemic racism vs. personal racism more than it makes the case that Americans of (more recent) African heritage can't be personally racist ["more recent" because according to the scientists all humans are of African heritage]. As I see it, people in that category can't be racist because for them a hatred of Americans of European heritage would be rational, whereas it is completely irrational Americans of European heritage to hate them. That would be like a mugger hating his victim for being his victim.