Michael Mosley, the filmmaker who captured the phenomenon, wrote on BBC's website about his encounters with Johnny, a young guevedoces who recently went through the transition himself: "Like the other Guevedoces, Johnny was brought up as a girl because he had no visible testes or penis and what appeared to be a vagina. It is only when he approached puberty that his penis grew and testicles descended," he writes.
Johnny, who was formally known as Felicita, said he remembers being treated as a girl, but also offers that he never felt fully comfortable. Throughout the piece, Mosley meets young Guevedoces who express similar sentiments. A previous researcher, studying the Guevedoces, determined "they don't have male genitalia when they are born is because they are deficient in an enzyme called 5-alpha-reductase, which normally converts testosterone into dihydro-testosterone."