Almost all of us are familiar of Testosterone male hormones but there is also more potent hormone than this, i.e. Dihydrotestosterone (DHT) which is form by the product of testosterone in the presence of special enzymes known as 5α- reductase. Dihydrotestosterone is very essential for the development of external genitalia (penis).
There are certain people in which the gene for 5α-reductase enzymes is mutated, it produces an interesting form of male, Individuals with this syndrome are born with male internal genitalia including testes, but they have female external genitalia and are usually raised as girls. However, when they reach puberty (age 12-14 years) Luteinizing hormone (LH) secretion and circulating testosterone levels are increased. Consequently, they began to develop male body contours and male libido.
At this point, they usually change their gender identities and become boys. The clitoris (female sensitive part homologous to male glans penis) enlarges to the point that some of the individuals can have intercourse with women, i.e. “penis at 12 syndrome”. Here there is the development of clitoris rather than penis. This enlargement probably occurs because with the high LH, enough testosterone is produced to overcome the need for DHT amplification in the genitalia.