Sex hormones are chemicals that regulate the development and maintenance of secondary sexual characteristics, as well as controlling the processes of puberty and reproduction in both males and females. These hormones include estrogen, progesterone, testosterone, and other related substances. They play a crucial role in determining an individual's sex characteristics, such as body hair distribution, breast development, and vocal pitch changes. Additionally, they are responsible for the onset of menstruation in females and sperm production in males. Overall, sex hormones help to regulate sexual activity and maintain a healthy reproductive system.