As early as the late sixties (yes, I vas dere), sf fandom was recognized by anthropologists, etc, as being a subculture in its own right...and, back then, it was 90% or 95% male. These days, it's more like 55%-45% male-to- female, and there are plenty of folks who've been around a long time...and many conventions also provide daycare for little ones.
I've often said that fandom is the world's largest non-geographical real community...and that cons are when we get to be a geographical one, when we can be with "our own kind".
Fandom, to a large degree, is a culture of loners. Most of us, who grew up in nonfannish families, were loners - not "popular", because we'd rather read than play, often not well "socialized"(1). What a culture is, is another discussion (What is a Culture)...but I make the distinction that the difference between sub- and culture is when more than half of the new members of the group come from within the group (i.e., kids of the members). Fandom's not there yet...but it's getting there.
1) "Socialized", as far as I can tell, appears to mean, "having learned to play mind games with others, never telling anyone how you feel, or if you dislike something (thereby never giving them a chance to change)". If this seems negative, it most certainly is. I do not have a lot of respect for what passes for "std. Amurkan society", when I see what it's done to so many good folks I've known.