I think we all suffer from confirmation bias Goose but I do see a lot of the archetypically "feminine" behaviours in DS's group as well as the archetypically "masculine" rough and tumble behaviours.
Well, yes, I think you see all the behaviours in both groups, and individual kids fall in all kinds of places in terms of their behaviour.
It's more a matter of whether there is a gap in the behaviour of the group as a whole, like with most sociological sorts of questions. If there is a tendency for there to be some differences it can also tend to be magnified by the way culture responds to that tendency.
My experience has been that this sort of behaviour really has the clearest sex based gap in the teen years.
As far as it goes though, I think there are some objective things we can point to. One is that men are more physically aggressive, pretty much across cultures, and if women are less so it would tend to mean they will express hierarchical power in other ways instead. Boys' language development is on a different curve, including later puberty, and something of a gap seems to remain even in adults. And I think there are some good studies about the way women use language in female groups compared to men and their social groupings more generally that suggests they behave somewhat differently.
Sometimes you hear people talk about women's social groups being more cooperative or democratic or less hierarchical, but I'm not sure that's quite the case, I think often the relations are just less obvious. It looks like everyone is hashing stuff out together and maybe in a way they are. But if you charted the relationships and power relationships out on some sort of link analysis chart, they would be there, negotiated largely through language.