"Not all blacks are like that, surely. But they DO have a major tendency towards violence as a group, a fact demonstrated by the size of their prison population, and a fact glorified in their music and "gangster" lifestyle."
Think it out a little more carefully. Culture is a set of group beliefs and values.
White guys in the south like fishing and Nascar. Not all, but a lot of them do. Probably a majority. So, does that happen because that's just what white guys do? It's in their DNA? Why is it more pronounced in the south? I'm white, I don't really care for fishing or Nascar.
Or maybe it's what one sees and hears growing up? Your dad and uncles do it, the kids you know like it, so you do too.
Is it possible that happens with violence? Do you think that maybe a black kid raised exactly how a white kid is raised will turn out the same?
I do.
You may not believe this, but I agree with you. But regardless of the root cause, it's fact. Blacks, as a group, have a greater propensity to violence than say, Swedes.
And it would be easy to dismiss the phenomenon in the US as "the legacy of racism", except that you only have to look to the incredible level of atrocities committed by Black Africans against other Black Africans to realize that this is a societal problem, a problem of their culture, which permits such violence at little or no provocation, and not something a few good wishes, pleasantries and a set of blinders will cure.
Culture has nearly everything to do with it, not race. But it is culture that defines the race.