Well, there are jobs that are statistically more appealing to women or men. In some of the Scandinavian countries where the opportunities to pursue any carrier are practically equal for both of the genders there are still jobs that are primarily either male or female. For example men don't want to do nursing. The girls are kicking boys asses academically but they still choose not to go into engineering even though they are being actively recruited by the universities. Another example for the Americans: after the U.S. military is started accepting women, how come the military isn't now 50 / 50 male to female? Now, there are some field that have seen noticeable changes after increased gender equality like for example medicine. Why is this happening in medicine and not engineering? Because medicine is on average more interesting to women than engineering. Why is this? culture? Nature or nurture? Who knows.
Looking at this forum or Youtube, it seems that there are more men interested in filmmaking than women. Assuming that gender plays no role in success (beacuse of different treatment etc.), the ratio of successful female directors to successful male directors would have to be same as the ratio of women interested in filmmaking to men interested in filmmaking. If you could calculate these ratios, you could determine if being a woman is a hindrance/ women are being underrepresented or if being a woman is an asset. Currently it probably is a slight hindrance if you are trying to get a studio gig and probably makes a very small difference in the indie world.
WHile I agree there will be of course a natural variation to career preferences amongst the genders (there are of course, genetic differences between sexes) my point was that these differences are largely accentuated by societal pressures and expectations.
I can't say a lot on Scandinavian countries, given I've not lived there and done little study on them outside news articles; but gender roles and expectations still play a huge role in our society. New Zealand, where I'm from tries to sell itself as a progressive country - and for the most part, the country is very gender neutral and forward thinking. But whilst opportunity is relatively equal, you are still raised as a child to believe that if you're a boy taht you should like the colour blue, play with lego and like fixing things (personally I think filmmaking appeals to me as an artform which I can approach very scientifically - I'm not sure if others see it that way too), whereas girls like pink, play with barbie dolls and are more interested in humanities. Universities here actively recruit females in the male dominated fields - but regardless, there is immediate suspicion and prejudices subtly put on a woman in engineering. It's not too bad, and imagine it was a lot worse, but if she's attractive I noticed a number male peers would view her as a sexual object, and if not, then she was pretty much segregated from the group (yet these guys had female friends in other faculties).
So I think, at least part of the reason that female's are uninterested in certain careers is due to societal conditioning. Applying that to film; film seems to be generally thought of as a masculine art form. Outside actresses (who, bar a few struggle to maintain careers once their looks fade) the general public would likely be unable to name many female filmmakers. A lot of the stories we tell are centred around male protagonists, and it hasn't been until the last few generations of filmmakers that more in depth female rolls started to exist (not that they didn't, it's just compared to men, you're much likely to have a female who represents little more than sexual desire). It's also a kinda nerdy thing to like films and want to make them as a kid - at least it was where i grew up -, and nerd subculture which for I guess a number of reasons (maybe related to boy play with lego, girls play with barbie) is largely dominated by males. So girls are naturally going to be less likely to be attracted to making films. Those who are probably wouldn't have many friends interested to encourage their interest.
So, again, it's kinda a vicious cycle. Certainly I do believe it's getting better, but we can't ignore the role that history and society played in creating that imbalance. Maybe in several generations the ratio will have improved and steadied out, perhaps indicating more a natural inclination for a certain genders to have interest in film. In my film papers (granted, at uni, not film school, so they're more academically inclined), as a male, I am massively outnumbered by females (about 5:1) - so I do question whether there is less interest from females.