Without being in beta, a lot of the (official as opposed to leaked) information we get is pretty limited.
One thing that is clear already is that Destruction classes are more gender specific than Order ones. Greenskins technically don’t have a gender because they are a kind of fungus but they all look male to me. We don’t know if sorceresses and witch elves will be restricted to female but it sounds likely. We haven’t seen any pictures of female marauders or chosen. This is not leaving people with a lot of choice on the destruction side if they want to play a female character who doesn’t look like a tarty dominatrix.
Does this really matter? Idris and I have played both male and female characters and had fun with them. But a lot of people do like to play characters of the same gender as themselves. It’s easier to identify, people talk to you in a manner you are used to, you don’t have to worry about whether you should pretend to be the other gender in chat or not.
So I think a lot of female players will tend to order, and since a lot of us play in couples there will be a trend for the older married/coupled players to go order. I’ll be amazed if Order isn’t the higher population side, partly down to this.
There’s a long thread about this on the warhammer alliance forums.