As a writer and mod from years ago, I don't believe in caps on gender. I feel like it screws with possibly line filling as much as just new blood coming in. Some writers aren't comfortable playing one gender vs the other, while others might really want a brother/sister but they can't have the writer who wants to fill the line do so, due to a cap. I do, however, believe in comms posting rules that state 'you can have x number of characters but at least x number must be male/female' so they guarantee those writers who want to have a ton of characters keep the ratio more fair.