kids will emulate what they see, if it appeals to them and seems to have a positive effect.

And all the available evidence makes it crystal clear that sexual expression--in either subtle or overt ways--is one of the things that young girls enjoy doing. Inundating them with the cultural belief that it's "inappropriate" for them to do so because they are "too young" to express themselves in such a manner doesn't change the fact that they obviously do have a sense of sexual identity, and making the expression of it "naughty" from a cultural standpoint may fuel their fire to express it all the more.