Sexual orientation is an enduring personal quality that inclines people to feel romantic or sexual attraction (or a combination of these) to persons of the opposite sex or gender, the same sex or gender, or to both sexes or more than one gender. These attractions are generally subsumed under heterosexuality, homosexuality, and bisexuality, while asexuality (the lack of sexual attraction to others) is sometimes identified as the fourth category. These categories are aspects of the more nuanced nature of sexual identity. For example, people may use other labels, such as pansexual or polysexual, or none at all. According to the American Psychological Association, sexual orientation "also refers to a person's sense of identity based on those attractions, related behaviors, and membership in a community of others who share those attractions". (Full article...)