Caporegime
They are more likely to be arrested, perhaps, or more likely to be in poor economic situations, or more likely to be the subject of racial discrimination. This doesn't necessarily correlate to black people committing more crimes.
Yes, there are many black people with culture different to the natives, but that changes generation by generation. Those that are my age (24) aren't culturally very different to myself.
No, it's a fact that they are more likely to commit a crime. Unfortunate as this is it cannot be disputed. A quick google of UK crime statitics by race will show this to you. As I say the causes for this are the point in question but the fact still remains. It's by the by however as the only reason I stated it was to illustrate that there are differences.
Also, yes whilst culture changes generation by generation we're not talking about 2nd 3rd or 4th generation immigrants here. We're talking about 1st gen. Those who grew up in the birth country of their parents and thus will have a substantially different culture.