Sexual Orientation is a term used to describe our patterns of emotional, romantic, and sexual attraction—and our sense of personal and social identity based on those attractions. A person's sexual orientation is not a black or white matter; sexual orientation exists along a continuum, with exclusive attraction to the opposite sex on one end of the continuum and exclusive attraction to the same sex on the other.
Heterosexuality (attraction to members of the opposite sex), homosexuality (attraction to members of the same sex), and bisexuality (attraction to members of either sex) are the three most commonly discussed categories of sexual orientation, though are by no means the only categories in the world of sexual identification labels. (Queer, for example, is useful for its non-specificity to orientation, and acts as an umbrella term.)
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 into its underpinnings frequently focuses on the role of genes, environment, brain structure, and hormones.