It’s interesting, assuming he’s right (for the sake of this chain of thought), what would be the statistical relation to being black. In which part. Say, Dwight is not such a common name and how often do black Americans use it as compared to the rest. Or maybe there’s some rhythmic or melodic thing in names which people in different groups follow differently.
EDIT: And while a guy named Jackson can be anything, a guy named Jebrowski is most likely not black. Black people would usually get English\Irish\Welsh\Scottish\German\whatever names, because those were the names of their former, sorry, owners. There weren’t a lot of Poles, especially owning slaves, in the new world at the time this was happening.
EDIT2: So there is a difference along racial lines.