Sexual orientation describes patterns of emotional, romantic, and sexual attraction—and one's sense of personal and social identity based on those attractions. A person's sexual orientation is not an either/or matter; sexual orientation exists along a continuum, with attraction exclusively to the opposite sex on one end of the continuum and attraction exclusively to the same sex on the other end.
Heterosexuality (attraction to members of the opposite sex), homosexuality (attraction to members of the same sex), and bisexuality (attraction to members of both sexes) are the three most commonly discussed categories of sexual orientation, although they are by no means the only ones in the world of sexual identification. The designation queer, for example, is used by some for its non-specificity to orientation, and acts as an umbrella term for non-heterosexual identities. Pansexual and omnisexual are terms gaining currency as the binary division of gender itself is called into question in some subcultures.
Few issues are as hotly contested as what determines a person's sexual orientation. While most scientists agree that nature and nurture both play complex roles, the determinants of sexual orientation are still poorly understood. Current research frequently focuses on the role of genes, environment, brain structure, and hormones.