I'm working off observation, not theory. I've heard speculation on the subject, but nothing that sounds convincing and nothing that makes testable predictions.

Looking at the statistics here, it looks like the fandom is even more male-dominated than I had thought. The smof are pretty much all male; I can think of only one exception. The show's writers are mostly female.

The average MLP fan is a good deal younger than the average LWer. Both are very likely to be white.