Sex - Basic Aspects of Human Sexuality

The Role of Hormones:
How do the hormones determine a person's sexual development?

In everyday language, people often distinguish between 'female' and 'male' hormones. However, this is misleading since both kinds of hormones are present in the bodies of both sexes. Typical of one or the other sex is the balance of these hormones which varies in different phases of a person’s life:

B e f o r e  b i r t h
1. Primary sexual characteristics: Between the 12th and 17th week of pregnancy the fetus develops into a female or male, and this means, first of all, the formation of female or male sex organs. During this period, the level of testosterone is ten times higher in the male than in the female fetus. After that, the level is reduced and remains equal to that of the female until the onset of puberty, when it rises again.
2. Brain: Prenatal hormonal influences also produce a different development of the female or male brain. This is evident, for example, in the female pituitary gland which, in contrast to its male counterpart, remains capable of reacting in monthly cycles (menstruation). Because of these and other differences, one has even introduced the concept of “cerebral sex” as an additional factor in the determination of sex. However, it is still unclear if and how far these brain differences really determine the biological or psychosocial aspects of sex and behavior. Much more research is needed.

D u r i n g  p u b e r t y
During puberty the level of testosterone is slightly higher in boys than in girls. At the same time, the level of estrogen is much higher in girls than in boys. These differences in the hormonal balance contribute to the development of the secondary sexual characteristics.