I understand. Though. I was responding to your rhetorical questions of: what is black culture? What is white culture? You stated that there were no 'compelling' explanations to make you believe in the existence of either.
There is Black culture, though I also stated that not every brown American subscribes. Just like every Mexican or Chinese person or Spaniard does not subscribe to a culture associated with that racial/ethnic identity.
I think the more relevant question is: what are “black” people? or what are “white” people? to make the point of groups not being monolithic. Because then we could break down the numerous ethnicities that exist under each category. After all, mass media never says “a black culture” got arrested. They use the all-encompassing term “black”, for example, which is incorrect.