Men and women think, act, and feel differently because of differences in brain structure and function. These differences, due to chromosomal patterning and hormones, emerge early in utero and affect a range of masculine and feminine behaviors. But, despite these differences, males and females—biologically—are actually very similar. Does that indicate that gender role stereotypes are perpetuated by society and culture?
Male and female embryos are indistinguishable until the male Y chromosome begins promoting the production of testosterone and male sex hormones. The presence of these sex hormones causes the male brain to develop differently than the female brain, especially in areas where sex hormone receptors are abundant. Genetic abnormalities can sometimes cause genital ambiguities when features from both sexes are present.
Besides affecting the functioning and development of sex organs, sex hormones also appear to impact behavior. Testosterone, which is produced in greater quantities in males, is believed to effect physical aggression—a behavior regarded as "typically male" in our society.
David Uttal states that "we tend to overemphasize gender differences," which may have to do with the human need to categorize our experiences to make sense of the world. Early in life, when children discover that two gender types exist, they too look for clues to help them discern the group to which they belong. Gender differences are diminishing as women today increasingly enter professions traditionally occupied by men. The degree to which we conform to gender-role stereotyping ultimately depicts how our world will look.