My two cents? Sure, why not?
I've always felt that the difference stems a lot from how each gender is raised differently. I mean, come on- say a little girl falls down and scrapes her knee. What does she get? "Aww, it's okay, cry, let it out, let me kiss it and make it better." What about a little boy? "Stop crying, you baby, you're not gonna die, suck it up, be a man, etcetera." And we all know how healthy pent-up emotions are. This pretty well demonstrates how males are very commonly instructed to hide their emotions from early childhood, whereas it's okay for girls and women to cry and be generally emotional. Pent-up emotion inevitably leads to violent outbursts, whether verbal, physical, or any other way you can think of. There really shouldn't be this gap between the genders. At the risk of sonding preachy, equality's pretty cool.
So are males more violent than females? I guess one could argue that. Using the various armed forces and the ratio of males to females as an example really doesn't cut it. It wasn't allowed, let alone "proper" for women to be involved in such things. Now that's it's acceptable, it's becoming common. Still, you could look at how many prominent male serial killers there are and compare it to the number of females (I can only think of one). I don't know. To me, it's not possible to judge either way. There doesn't have to be a more violent gender.
But anyway...girls are also taught to be more nurturing when they're young. They play with baby dolls while boys get toy soldiers. That should say it right there! I saw a special on TV- I don't know where- where a boy and a girl were each brought into a room separately, and they were given a doll whose head was basically designed to fall off. When it did, the girl's instinct was to help it. The boy didn't care. And that's also part of it- instinct. Humans are animals, complete with instinct.
Now you've got me rambling, so I'll quit while I'm ahead. In conclusion, no violent gender, instinct, way kids are raised, etcetera. I close by saying that girls like violent video games just as much as guys do. I'm very touchy about that.
One last thing: Gabriel's girls=evil pic? Hilarious.