This brings up the issue of lying. Differences in male and female views of aggression or assertive behavior become apparent in Turkle's article- bitch vs. empowered woman etc. Turkle brings up this question. We have immovable identites, more or less, from very early on. Turkle's example of the man interacting in MUDs as a woman to help other women and his experiences illustrates this point.
Sex is predicated on gender.
These ideas represent a cycle with the conclusion that there is no origin of gender.