The Dominican village where girls become boys at age 12

Born female, did not grow a penis until he reached his 12th birthday.

Other kids in the town of Salinas cope with what is called “Guevedoces”, where a penis does not grow until the child is 12 years old.

One in 90 children in Salinas face this rare genetic disorder, telegraph.co.uk reported.

But the second hit of testosterone that comes with puberty seems to do the trick: At this point, a Guevedoce grows a penis and testicles and develops a more muscular build.

In 1974, Doctor Julianne Imperato, an endocrinologist from Cornell University went to study the children of the Dominican Republic who had been rumoured to have been born with female genitalia but who had developed male genitalia at puberty.

Presenters meet Johnny, 24, a man brought up as a girl called Felicitia.

‘I was born at home instead of in a hospital. He said: “I did not feel good, I no longer liked to wear a skirt, and I was no longer drawn to play with girls”. In his early years, he went to school wearing dresses and was treated like a normal baby girl.

However, “guevedoces” are missing the enzyme that triggers the hormone surge (while still carrying the Y chromosome) and are born female.

A little girl named Carla is now going through the same transformation, aged nine.

Intrigued by rumors of girls turning into boys in the remote area of the Dominican Republic, Imperato-McGinley set out to investigate the reasoning behind this phenomenon.

When Johnny made the transition from girl to boy, he struggled to fit in with the rest of the children.

His story will be featured in a new series Countdown To Life – The Extraordinary Making Of You by British broadcaster BBC 2. “When I changed I was happy with my life”, Johnny says.

Despite being brought up as girls for the majority of their lives, most young guevedoces identify strongly as heterosexuals and express a disdain for women’s lifestyles.

According to the BBC, Dr. Imperanto’s research was picked up by American pharmaceutical giant Merck, now working on a drug called finasteride that mimics the lack of dihydro-testosterone seen in “guevedoces”. She traveled there and learned that the phenomenon was due to a deficiency in 5-α-reductase which are enzymes involved in steroid metabolism and which normally convert testosterone into DHT. The drug is a blessing to men because it blocks the action of 5-α-reductase, which is used to treat mild enlargement of the prostate and male pattern baldness. Most have decreased amounts of facial hair and smaller prostate glands relative to the average male.