The authors, (one of whom is a neurologist) demonstrate that instead of physiology determining behavior in relation to apparent gender differences, the precise opposite is true: namely, external social influence shapes behavior and those differences in behavior contribute to any observed differences in neuro-anatomy and neuro-physiology. In principle, it is the exact same phenomenon that accounts for the way learning particular types of skills and emphasizing particular kinds of social interactions have been empirically demonstrated to stimulate characteristic changes in human brains.

Conclusion

The authors conclude...

To the extent conditioning promotes "sensitivity" in girls and "dominance" in boys (for just one of many examples) or traits generally associated with femininity and masculinity (respectively), those influences will be reflected in gender-based tendencies. However, all of those differences are functions of external influences and there are virtually no identifiable inherent differences between males and females absent those influences.