As an anthropology enthusiast I was absolutely fascinated by the points Holly made about the history of thought surrounding gender, and the one sex model wherein all people lived on a continuum of a single gender and women were simply men experiencing a very extreme version of what is known in the vernacular as "scared turtle syndrome".
One Sex Paradigm Transexual Action Barbie is a fun interactive teaching tool for this train of thought. Her spring loaded penis retracts into the body to form a one sex paradigm vagina, wherein, despite being cold and clammy, she can house the blessed seed of a warmer male counterpart. Releasing the spring explosively jolts her into the warmer, upper world of masculinity (small parts may cause choking hazard, not recommended for children under three).
Legends say a tiny penis still haunts the actlab......