Imagine the following situation: planned or not, you and your partner (or partner) discover that you will have a baby. By the fourth month, an exam confirms the sex of the child and you will have a girl. From there everything is made for this, from trousseau, a decorated room, gifts and, among other things, the choice of name. This alone can last even longer than expected, depending on the couple's level of indecision.

With the name already chosen and all the necessary structure, comes the day of birth. The happiness is huge and thus begins the girl's creation. She grows up with her feminine habits, toys, dolls, makeup, among other things, and thus goes through childhood, reaching puberty. It is at this time that suddenly something very strange happens: the reproductive organ is transformed and soon the girl has a penis, and develops beard, thick voice and muscles of man.

Johnny is one of the characters in the BBC documentary. Officially, your name is Felicita

Believe it or not, this really happens and has been frequent in the Dominican Republic, in a condition that is locally known as “guevedoces” or “penis at twelve”. These cases are the main theme of a new BBC series of documentaries that is drawing attention to the issue.

Genetically, these “girls” have always been men, but due to an enzymatic failure, the development of the external genital region is blocked and maintains the feminine characteristic, even if, internally, the reproductive system is male. But how and why does this happen?

The development of the male reproductive system depends on the action of two specific hormones, testosterone and dihydrotestosterone (DHT). These, in turn, are influenced by an enzyme, more precisely transforming the first hormone into the second. If a person has an enzyme flaw, DHT production is impaired and this causes the condition to be seen. This situation occurs after the tenth week of gestation, when, until then, the fetus has the normal appearance of a male individual.

With excess testosterone, the Guedoces develop the entire internal male reproductive system, with prostate, vas deferens and testicles, but with the absence of DHT, the outside ends up with the female characteristic, ie clitoris and lips . There is also a cavity that, because it does not have a uterus, fallopian tubes and ovaries, is known as a “blind vaginal sac”.

Illustration shows the difference between the common male reproductive system (left) and the DHT deficient reproductive system.

Thus, roughly speaking, and physically speaking, these individuals are "boys on the inside and girls on the outside." So they grow up like girls until their teens, when, with the onset of puberty, they start producing high levels of testosterone. This causes the penis to develop, in addition to the thickening of speech and the growth of facial hair common to age, to develop and the scrotum to appear.

Soon, the Guedoces go through the same developmental process as any other boy, but their reproductive organ, until it grows, is the size of a clitoris. After this process, most end up adapting to the new male body.