Sexual Facts



  • The sexual development of girls and boys depends on the sex hormones.
  • Sex hormones control the development of primary and secondary sexual characteristics, and regulate all sex-related processes such as sperm and egg production.
  • Primary sexual characteristics are the major sexual organs, in particular the genitals.
  • Secondary sexual characteristics are other differences between the sexes, such as men’s beards.
  • There are three main types of sex hormone –androgens, estrogen and progesterone.
  • Androgens are male hormones such as testosterone. They make a boy’s body develop features such as a beard, deepen his voice and make his penis grow.
  • Estrogen is the female hormone made mainly in the ovaries. It not only makes a girl develop her sexual organs, but controls her monthly menstrual cycle.
  • Progesterone is the female hormone that prepares a girl’s uterus (womb) for pregnancy every month.
  • Some contraceptive pills have estrogen in them to prevent the ovaries releasing their egg cells.
  • Boys have female sex hormones and girls have male sex hormones, but they usually have no effect.