Growing a penis at 12: the ’Guevedoce’ boys of the Dominican Republic - Telegraph
▻http://www.telegraph.co.uk/news/science/science-news/11874983/Dr-Michael-Mosely-growing-a-penis-at-12.html
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.
(...) 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.