Guevedoces - Sexual Differentiation, Development of External Genitalia
Boys appear to be girls at birth and turn into males at puberty. In a small village in the Dominican Republic, approximately 1:90 boys are born looking like girls at birth. At puberty (~age 12) they begin to develop masculine features such as facial hair, deepening of their voice, and a PENIS! In their village, these boys are called “Guevedoces”
Females have 2 X chromosomes while males have an X and a Y chromosome pair. The Y chromosome has a special gene called the SRY gene that is activated and is responsible for the internal development of the testes. In the testes a very important sex hormone is made called testosterone. Testosterone is then converted into a more potent form called DHT (dihydrotestosterone) by an enzyme called 5-a reductase. DHT is responsible for the development of the external male genitalia such as the penis and scrotum.
Guevedoces have the XY chromosome pair with the activated SRY gene, internal testes that produce testosterone, however, they do not have the enzyme 5-a reductase so their external genitalia never develop, and this is the reason why they look like girls when they are born
During puberty males experience a surge of testosterone. This dramatic increase of testosterone leads to the growth of male external genitalia, specifically, a penis, from what was originally thought to be a clitoris.
The girl to boy life transformation in the lives of the Guevedoces is joyfully celebrated amongst family and friends. This transition is effortless and non-discriminating as this is a frequent occurrence in this part of the world.