I put Jews because Orthodox Jews are among the most insular people out there, as for non-Orthodox Jews I think they vary greatly. I find East Asians to be amenable to friendship when they are in small numbers, when there are tonnes of them around they will stick together. Blacks are pretty happy to be friendly with Whites (again, unless they are in a group or especially aggreived about something), although it is usually a process which involves the latter assuming the cultural affectations of the former (rap music etc). I don't see many Black rock fans, but I could have a skewed picture I suppose.