Teacher, pilot, nurse or engineer? Sex hormones strongly influence people's interests, which affect the kinds of occupations they choose, according to psychologists.

"Our results provide strong support for hormonal influences on interest in occupations characterized by working with things versus people," said Adriene M. Beltz, graduate student in psychology, working with Sheri A. Berenbaum, professor of psychology and pediatrics, Penn State.

Berenbaum and her team looked at people's interest in occupations that exhibit sex differences in the general population and are relevant to science, technology, engineering and mathematics (STEM) careers. The researchers studied teenagers and young adults with congenital adrenal hyperplasia -- a genetic condition -- and their siblings who do not have CAH.

People with CAH are exposed to more androgen -- a type of male sex hormone -- than is normal while in the uterus. Females with CAH are genetically female and are treated as females, but their interests tend to be more similar to stereotypically male ones.

The researchers report in the current issue of Hormones and Behavior that females with CAH were significantly more interested than females without CAH in careers related to things compared to careers related to people. The researchers also found that career interests directly corresponded to the amount of androgen exposure the females with CAH experienced -- those exposed to the most androgen in the uterus showed the most interest in things versus people.

"We took advantage of a natural experiment," said Berenbaum. "We're suggesting that these interests are pretty early developing."

Females without CAH had less interest than males in occupations related to things, such as engineer or surgeon, and more interest in careers focused on interacting with people, such as social worker or teacher. There was no significant difference reported between males with CAH and males without the condition.

"We found there is a biological influence on that interest toward things, so maybe women aren't going into STEM careers because what they're interested in -- people -- isn't consistent with an interest in STEM careers," said Beltz. "Maybe we could show females ways in which an interest in people is compatible with STEM careers."

The researchers asked the participants to rate each item in a list of 64 occupations, according to whether they would like, dislike or were indifferent to doing that job. The occupations were grouped into six categories of careers -- realistic, investigative, artistic, social, enterprising and conventional. This list and the categories are based on a well-established and validated system often used by vocational counselors.

The realistic and investigative categories reflect thing-oriented careers like farmer and scientist, social and artistic categories reflect people-oriented jobs such as teacher and artist, and the enterprising category was in the middle with occupations like realtor and hotel manager.

Also working on this research was Jane L. Swanson, professor of counseling psychology, Southern Illinois University Carbondale.

The National Institutes of Health supported this research.