In Albania, there was a dearth of men after the internal wars in the 1400s. To make up for the lack of men, Albanian culture created "virgjinesha" (virgins). A virgjinesha is a woman who takes an oath to become a man and live a celibate life. Lisa Wade of Sociological Images wrote,
Since rights and responsibilities were strongly sex-typed, some families needed a “man” to accomplish certain things like buy land and pass down wealth. In response, some girls became “virgjinesha,” or sworn virgins. A sworn virgin was a socially-recognized man for the rest of “his” life (so long as the oath was kept). Many girls would take the oath after their father died. There are only about forty sworn virgins left; as women were granted more and more rights, fewer and fewer girls felt the need to adopt a male identity for themselves or their families.The SI post references a similar cultural practice in Afghanistan, but I learned about cultures in Africa that had women take on the social presence of a man to inherit their fathers' wealth, should there be no sons to inherit it. These socially recognized males would take on wives who were allowed sexual freedom in order to produce an heir (hopefully a male). There are numerous examples beyond this that point to the flexible nature of gender (the socially proscribed role). In Western society, we correlate gender and sex (the biological identification). This creates issues as people's sex and gender no longer correlate as traditional mores proscribe (most notably, same-sex marriage). It goes to show that though the new fluidity threatens our current structure, it does not mean chaos will reign. This only means we have to come up with a new structure that accommodates this discrepancies more and divorces some ideas about sex and gender.
For more on the topic, please visit the NYTimes article and the accompanying slideshow.