In primary school, Bernd had a lot of black classmates, since he grew up in a rather poor region. He was friends with some of them. Most of them didn't get the "recommendation" to go to the highest level of our secondary school system. The one black friend who came to the same school as Bernd then developed different interests, so we lost contact over the next years. He's a surgeon now, our mothers are still friends.
In Bernd's university, there were even fewer black students than in high school and at Bernd's company, there's not a single black person.
>Do Bernds and blacks mix?
I don't see why not, but some mechanisms in society seem to work against it.