Androsterone, for one, is a HORMONE that is produced in the adrenal glands of both males and females. It is an androgen, which is a type of steroid HORMONE that is responsible for the development of male characteristics. It is also involved in the regulation of sexual behavior and aggression. In men, it is the primary male sex HORMONE and is responsible for the development of secondary sexual characteristics such as facial hair, deep voice, and increased muscle mass. In women, it plays a role in the regulation of the menstrual cycle and fertility.