Heterosexuality

Sexual attraction to members of the opposite sex.

The sex drive, or sexual desire, is an unlearned, powerful drive that humans share with other animal species. Heterosexuals experience sexual desire in relation to members of the opposite sex. This contrasts with homosexuals, where the object of sexual desire is a member of one's own sex. Most researchers believe that children begin to notice physical differences between males and females by about age two. As children grow, they learn about sex roles and sex differences by observing their parents and other adults, including teachers, child care providers, and from play experiences and the attitudes and behavior of peers. Gender identity becomes firmly established, that is, the young boy understands that he is a boy, and thinks of himself as a boy.

Sex researcher Alfred Kinsey (1894-1956), who founded the Institute for Sex Research at Indiana University in 1942, believed that sexual orientation in humans is complex, ranging from exclusively homosexual to exclusively heterosexual, with most people's sexual desires falling somewhere between the two. In fact, some individuals practice bisexuality, that is, they engage in sexual relations with both members of their own sex and members of the opposite sex. Kinsey's controversial study, popularly known as the "Kinsey Report," was published in 1948 under the title Sexual Behavior in the Human Male. His theory caused heated public discussion, since sexual behavior was considered a taboo subject for public discussion and study. In fact, until the late 1960s, any sexual behavior outside of exclusively heterosexual was considered either a mental illness or perversion. Although homosexuality continues to be prohibited by law in many locales, it is no longer listed as a mental disorder by the American Psychiatric Association.

Although much research into underlying causes of sexual orientation has been done, little conclusion evidence has emerged about why one individual is heterosexual and another homosexual. Researchers have studied biological and genetic determinants, hormone levels, and environmental factors. It seems from evidence available in the mid-1990s that environmental and biological factors combine in the complex process of human development to establish sexual orientation.