Better late than never! Any if you have this issue? Growing a penis at 12: the 'Guevedoce' boys of the Dominican Republic Scientists and BBC presenter travelled to the Dominican Republic to meet the 'Guevedoce' males who do not grow a penis until puberty 2K 330 6 0 2K Email Michael Mosely in Countdown to Life – the extraordinary making of you By Dr Michael Mosely 12:01AM BST 20 Sep 2015 375 Comments I hated going through puberty; voice cracking, swinging moods, older brother laughing at me. But compared to Johnny, who lives in a small town in the Dominican Republic, I had it easy. We came across Johnny when we were filming for a new BBC2 series, “Countdown to Life”, which looks at the consequences of normal, and abnormal, developments in the womb. Johnny is known as a “Guevedoce”, which literally means, “penis at twelve”. And the reason he’s called that is because, like 1 in 90 of the boys in the area, he first started to grow a penis when he was going through puberty. 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. Johnny, who is now in his 20s, was once known as Felicita. He was brought up as a girl and remembers going to school in a little red dress. When he was young he would happily play with other little girls, but after the age of seven he started to change “I did not feel good, I no longer liked to wear a skirt, and I was no longer drawn to play with girls. All I wanted to do is play with toy guns and boys” When he turned obviously male he was teased at school because”, as he put it, “it is hard to imagine a girl that is now is a boy”. Johnny One of the first people to study this unusual condition was Dr Julianne Imperato, a Cornell endocrinologist. She travelled to this remote part of the Dominican Republic in the 1970s because of strange rumours about girls turning into boys She eventually unraveled the mystery of what is going on and by doing so helped make a surprising medical breakthrough. At conception we all inherit a set of genes from our parents that will, in time instruct our bodies to make us male or female. But for the first few weeks of our lives human embryos are neither. Instead we have a protrusion called a tubercle. If you’re genetically male the Y chromosome instructs the gonads to become testicles. They also send testosterone to the tubercle, where it is converted into a potent hormone called dihydro-testosterone This transforms the tubercle into a penis. If you’re female and don’t make dihydro-testosterone then your tubercle becomes a clitoris. 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. So they appear female when they are born, but around puberty, when they get another surge of testosterone, they sprout muscles, testes and a penis. Apart from being slightly undersized everything works and the Guavadoces normally live out their lives as men, albeit with wispy beards and small prostates. 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 Since he’s become male Johnny has had a number of short term girlfriends, but he is still looking for the love of his life. “I’d like to get married and have children, a partner who will stand by me through good and bad”, he sighs wistfully.