出生前

1.初級性徵：在懷孕的第12-17周裏，胎兒發育成女性或男性，這首先意味著女性和男性性器官的形成。在這個時期，男胎睾丸激素的水準是女胎的十倍。此後，男胎睾丸激素水準下降並維持與女胎相等的水準，直到青春期啟動為止。到這個時候，激素水準又升高。

2.腦：出生前，激素的影響同樣導致女性和男性腦發育發生差別。差別是明顯的，例如，與男性的垂體對比，女性的垂體仍然維持按月的迴圈週期（月經）。因為這些個差異和其他的差異，有人甚至已經引入了“腦性別”的概念，把它作為決定人的性的附加因素。但是，仍然不清楚兩性腦的這些差異是否和在多大程度上真正決定了性的生物或社會心理方面以及行為方面的差異。需要更多的研究來證實。

青春期
在青春期，睾丸激素的水準是男孩稍微高與女孩。同時，雌激素水準是女孩遠高於男孩。這些個在激素平衡上的差異，對次級性徵的發育發揮著作用。

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:

Before  birth
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.

During  puberty
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.