Related to the topic gender is sexual orientation, or a person's sexual, romantic, affectionate, and emotional attraction to members of the same sex, the opposite sex, or both. A person who is attracted to members of the opposite sex is heterosexual, or “straight.” A person who is attracted to members of the same sex is homosexual, or “gay” (male) or “lesbian” (female). A person who is attracted to members of both sexes is bisexual, or “bi.”
Most sociologists today refer to sexual orientation rather than sexual preference. The latter implies that sexual attraction is a choice, which many researchers believe is not the case.
In the 1940s and 1950s, Alfred Kinsey and his associates discovered that sexual orientation exists along a continuum. Prior to Kinsey's research into the sexual habits of Americans, experts generally believed that most individuals were either heterosexual or homosexual. Kinsey speculated that the categories of sexual orientation were not so distinct. On his surveys, many Americans reported having had at least minimal attraction to members of the same gender, although most had never acted on this attraction. In short, Kinsey and colleagues brought to the attention of medical science the notion of heterosexuality, homosexuality, and bisexuality all being separate but related sexual orientations.