Well, I said there are good and bad on both sides; I didn't say anything about the proportions of each!
Seriously though, trying to figure out how insurance companies come up with premiums will drive you nuts, since the factors they say they take into account are often inconsistent.
On the basic male vs. female issue though, I've seen it said that women's claims tend to be for more minor fender benders such as parking mishaps and the like, whereas men's claims tend to be for much greater amounts caused by more serious crashes. I guess the often-competitive male of the species is more likely to take chances with passing, forcing his way in at high speeds, etc.
I do have to say that I can't understand the way that some people's attitude changes as soon as they get behind the wheel of a car, and this does seem to be a predominantly male characteristic in my experience. I know several people -- all of them men -- who have the most easy-going, laid-back attitude to everything most of the time, but put them in the driver's seat and suddenly they become the most unforgiving, impatient people toward other road users you could imagine. I don't get it.