Now, yes, the majority of fen are female in some sense or another, but not all of us are. Also, this does not mean that all "female" fen are girly, are female-bodied, or even think of themselves as female. We can't say that fandom is this way because fen are already this way- it simply isn't the case. Yet the feminine tone and timbre of fandom is sufficient that it can change the behavior of less-feminine fen. I'm speaking mostly from my own experience here- I started off on LJ using gender-neutral pronouns and presentation, but within a week, I found it so difficult to try to maintain gender-neutrality (especially as I'm not trans-identified, and I do use a gendered set of pronouns in everyday life) in a context where most people assumed I was female that I gave up.
So how did fan culture get this way? And is it fan culture "at large," or is this a phenomenon specific to blog-based fandom? Can we or should we do anything about it? Because right now, our language and modes of interaction can exclude some fen or render them invisible, but as Riki Anne Wilchins (and half the rest of the activisty planet) has noted, identity politics sucks.
Please, please weigh in.