So the tradition from Europe is that you're supposed to emphasize the mind over the body, so you sing from a very kind of staid perspective. Again, there are charismatic white congregations all over, and they don't sing that way. But, you know, on the average.

Humor is so culturally based that when I try to tell a joke as me being a white American, if I tell other white Americans, they'll laugh. If I tell an African American, they might not laugh. In fact, they either might not find it funny, or they might find it offensive, and I didn't mean it to be offensive. So these are the sort of little things that build up over time, just like in a marriage. You know, the little things can build up over time.

What happens is sometimes these congregations will still have the white style of worship, even though they're mixed, because folks are willing to give up whatever they may have come with. So it's still quite a stretch for African Americans, yeah.

What sort of difficulties would happen when people of different cultures try to come together to worship? Tiny little things such as let's tell jokes with each other.

It happens a little bit more in the West, where there's more fluid - where everybody's originally from somewhere else. So they have a little bit more permission to do it. It happens the least, at the individual level at least, in the South, because the South has very strong, you know, set up black churches and white churches and a long history of that, and so it's a bigger social cost.

I think with President Obama there's going to be a discussion, because he himself is multiracial, because we have for the first time a non-white president. There's going to be talk about what does this mean? What is it? Are we in a new era?

We go where our family goes. We go where our friends are, and because our social networks are so segregated by race, we end up with what we have. We also find that, you know, if you're immigrants, you're not part of that history.