Do Girls Train To Become Women?

I have often suspected that as girls grow up, they go through a training period where they take on the attitudes, dress habits, poses, walking gaits, and more features as well, of fully grown women. Around the age of 12 to 14, I suspect the hormones are changing, and the attitude stuff begins, making them impossible to reason with. Meanwhile, they have the breast thing going on, and presumably the monthly cycle as well, and around this time they learn that they can actually call the shots, and manipulate the guys. Like this Gal:



What gets me is the look on her face, just full of glee and happiness, the reason being that she knows that it is true.