Johnny, 24, never felt comfortable as a girl, he started turning into a boy at seven years old. Photo: BBC

Puberty is a tough time for anyone but a small group in the Dominican Republic may have the toughest time of all.

The village of Salinas in the Caribbean island's Barahona Province has a remarkably high number of pseudohermaphrodites, also known as the ‘guevedoces’ which means ‘penis at 12’.

The transition involves around one in 90 females born in the area growing a penis and ultimately switching genders.

Cornell University endocrinologist Dr Julianne Imperato investigated the phenomenon in the 1970s and found that the guevedoces lacked male genitalia at birth.

This was because they were deficient in the 5-a-redutase enzyme, which converts testosterone into dihydro-testosterone in the womb.

Children who are born with the condition appear to be girls.

However, about the age of 12 their voices start to break and they start to grow male reproductive organs.

One young man named Johnny, 24, told BBC that he never felt comfortable as a girl.

Growing up he was known as Felicita and said while he used to wear a skirt to school he never liked dressing as a female.

“When they bought me girls' toys I never bothered playing with them,” he said.

“All I wanted to do was play with the boys."