A white brain is no different to a black brain.
You raise a white baby in a black area they will grow up with a black accent and act according to black culture. You raise a black baby in a white area they will grow up with a white accent and act according to white culture. Let's just assume here that the two cultures are different as in South Africa in some areas.
So what is my point - it's all about culture, class (economic circumstances, etc.) and how you were raised.
Saying that a black person is more likely to commit violent crimes is just pure nonsense as statement on it's own.
But throw in country, class and culture and it could very well be true, not because they are black but because of the aforementioned characteristics and circumstances. Gang life in the US for example, growing up in that environment.
But then the same could apply to whites (or any other race) cultures as well. It all depends on how you were raised, the culture you grow up in and so on.