He is known as a “Guevedoce”, meaning “penis at 12”, because his genitals did not develop until puberty.

The disorder was first discovered by a Cornell University endocrinologist Dr. Julianne Imperato. The Y chromosome also gives testosterone to the tubercle, which then converts it into a penis, through the use of a hormone call dihydro-testosterone. All fetuses have internal glands called gonads and a small bump between their legs called tubercle.

Gender kicks in when a fetus turns eight weeks. Sans this enzyme the external genitalia appear similar to that of a female clitoris and labia.

The 24-year-old boy like many others in his Salinas community was born with what is said to be a vagina. 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. She realized that the Guevedoces tended to have smaller prostates.

“I did not like to wear dresses and when I received girls’ toys, they never amused me”.

‘I was born at home instead of in a hospital. They literally change sex. But Johnny insists that he has always been a boy at heart.

Johnny, a child who was raised as a girl but later formed male organs, told the BBC he never felt comfortable doing “girly things”. “All I wanted to do was play with the boys”. “When I changed I was happy with my life”, he said.

“They are called the “Guevedoces”, ie the ’12-year penis”. She traveled to the Dominican republic after hearing unusual rumors of girls turning into boys, and eventually found out they were true. And in the four decades since there have been studies, more has been learned about the perfectly natural condition.

The story of these children who live in Salinas, an isolated village in the southwestern Dominican Republic, features in a new BBC science series “Countdown to Life – the extraordinary making of you”.

This rare phenomenon in the medical terminology is known as “pseudohermaphrodites” in which kids born appear to be girls till they attain puberty. “It is only when they are near puberty that the penis grows and testicles descend”.

The discovery of the guevedoces has apparently been very helpful to many men around the world.