Hmmm, its tough to say. Originally I'm from a place that I would consider a non-diverse place, and I was for gay marriages. And for the past five years, I've lived in a more diverse area and I'm still for it.
I voted for "For it: non-diverse place" in this case because my mind didn't change when I moved to a bigger city. But on the other hand, I don't know if I really believed it when I lived in the non-diverse town. It really took living in a more diverse area to cement in certian ideals (and weed out others).