WONDER:Girls grow a PENIS and then turn into BOYS when they hit puberty in beautiful Caribbean village

 BY SIOBHAN MCFADYEN

 There are three sexes in Salinas where being a pseudohermaphrodite is so common it's accepted alongside male and female.

 Countdown To Life presenter Dr Michael Mosley visits Salinas to meet the girls who morph into boys 

On the face of it, the small village of Salinas in the Barahona Province of the southwestern part of the Dominican Republic, is like many other Caribbean hideaways. The natives are friendly, there's sandy beaches and the sun beats down often - but there is one peculiarity that sets it apart from the rest of the world. At puberty one in 90 children born there make a natural transformation from girl to boy. Referred to as the ‘guevedoces’ which literally translates as ‘penis at 12’ - these children are known in medical terms as 'pseudohermaphrodite' - and feature in a new BBC 2 series called Countdown to Life - the Extraordinary Making of You.

 Happy: Johnny was born a female but became a man during puberty when his testosterone began to flow

 “I remember I used to wear a little red dress,” said Johnny who at 24 was once known as Felecitia and did not have a penis. “I was born at home instead of in a hospital. "They didn’t know what sex I was. “I went to school and I used to wear my skirt. I never liked to dress as a girl. "When they bought me girls toys I never bothered playing with them. All I wanted to do was play with the boys.” The guevedoces were uncovered by Cornell University endocrinologist Dr Julianne Imperato in the 1970s who travelled to the region to learn more about rumours that girls were morphing into boys. And in the four decades since there have been studies, more has been learned about the perfectly natural condition.

Accepted: the Guevedoces in the Dominican Republic are formed from a rare genetic disorder 

Believed to have transpired through a rare genetic disorder, the condition is caused by a missing enzyme that prevents the production the male sex hormone - dihydro-testosterone - in the womb - and creates what looks like a baby girl on birth. It is not until puberty, when testosterone flows, their voices break and they grow a male sexual reproductive organ that they become recognised as male. BBC presenter Dr Michael Mosley said: “I hated going through puberty; voice cracking, swinging moods, older brother laughing at me. But compared to Johnny, I had it easy. “Guevedoces are also sometimes called “machihembras” meaning “first a woman, then a man.” "When they’re born they look like girls with no testes and what appears to be a vagina. "It is only when they near puberty that the penis grows and testicles descend. “When Dr Imperato investigated the Guavadoces she discovered the reason they don’t have male genitalia at birth is because they are deficient in an enzyme called 5-α-reductase, which normally converts testosterone into dihydro-testosterone. “By a quirk of chance Dr Imperato’s research was picked up by the American pharmaceutical giant, Merck. "They used her discovery to create a drug called finasteride, which blocks the action of 5-α-reductase. “It is now widely used to treat benign enlargement of the prostate and male pattern baldness. For which, I’m sure, many men are truly grateful.” Dr Michael Mosley presents “Countdown to Life – the extraordinary making of you “ on Monday 21st September, BBC2, 9pm.