It's Hard to Be a Chick. No, Really
Being a female ain't easy. No, not because we have to struggle around in high heels, recall "Sex in the City" quotes at the drop of a hat, or deny ourselves the scrumptious double scoop of mint chocolate chip ice cream in order to lose two more pounds. No, it's because there's only a single gene struggling to keep us from becoming a male at any point in our lives.
The FoxL2 gene is present in every female, and it works by preventing the male gene, Sox9, from taking over and making us hairier, cruder and lewder. When the FoxL2 gene is turned off, a signal processes ovarian cells and turns them into cells that are typically only found in the testes and causes them to produce 100 times more testosterone than normal. Essentially, the ovaries turn into testes.
This "female gene" is active throughout a woman's lifetime, constantly maintaining her femininity, and her ovaries. According to researcher Robin Lovell-Badge, from the Medical Research Council's National Institute of Medical Research in London, this genetic manipulation could be an alternative to typical gender re-assignment surgeries: "It's still very speculative, but it's possible that this approach could produce an alternative to surgery and the removal of gonads -- ovaries and testes."
These findings mean that being male or female isn't a fixed state that's determined at birth, but instead a constant struggle that waxes and wanes. This may lead to further explanations on unwanted body hair and post-menopausal changes in women, such as deeper voices.
Source: Popular Science