Bodily changes at the time of puberty such as voice cracking and mood swings are all too common among boys worldwide. The transformation that some boys undergo at a remote village in the Dominican Republic is extraordinary - these boys grow a penis only when they hit puberty.
The story of these children who live in Salinas, an isolated village in the southwestern Dominican Republic, features in a new BBC science series "Countdown to Life - the extraordinary making of you".
One in 90 children in Salinas face this rare genetic disorder, telegraph.co.uk reported. In their village, these children are simply referred to as the 'guevedoces' - which literally translates as 'penis at 12'.
The disorder occurs because of a missing enzyme which prevents the production of a specific form of the male sex hormone - dihydro-testosterone - in the womb, the report said.
Because of this missing enzyme they appear to be born female with no testes and what appears to be a vagina. The male reproductive organs emerge during puberty at around 12 years of age due to a huge surge in testosterone.
So what should have happened in the womb happens around 12 years later. Their voices deepen and they finally grow a penis.