In the remote town of Salinas in the Dominican Republic, it’s strangely common for girls to turn into boys when they reach puberty.
Those with the condition are referred to as Guevedoces which translates to ‘penis at 12’ or Machihembras which translates to ‘first a woman, then a man’.
It’s thought that around two percent of the village’s babies are born with the condition.
So what’s behind this odd phenomenon?
In the womb, all babies – male and female – have a small bump between their legs called a tubercle.
At around the two month mark, babies with the Y chromosome begin producing dihydro-testosterone. This hormone causes the tubercle to turn into a penis.
However, if the enzyme that causes this hormone surge is missing, the male baby doesn’t grow a penis.
When puberty happens, a huge surge of testosterone is released, causing the male reproductive organs to finally appear.
Cornell University’s Dr Julianne Imperato-McGinley was the first to find the guevedoces when she travelled to the Dominican Republic in the 1970s.