Personally, I only recently come across the concept that fanfics are a female thing.

I've been reading fanfics for over 10 years, and in the various places I've hung out... none of them had more women than men. In fact, they have very few women at all, and it don't think it's because we men looked down on them.

Of course, I don't actually hang out on LJ, I don't even use mine, so it may be different here...