Heterosexual–homosexual continuum in the context of "Behavioral science"

Heterosexuality is romantic attraction, sexual attraction, or sexual behavior between people of the opposite sex or gender. As a sexual orientation, heterosexuality is "an enduring pattern of emotional, romantic, and/or sexual attractions" to people of the opposite sex. It "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." Someone who is heterosexual is commonly referred to as straight.

Along with bisexuality and homosexuality, heterosexuality is one of the three main categories of sexual orientation within the heterosexual–homosexual continuum. Across cultures, most people are heterosexual, and heterosexual activity is by far the most common type of sexual activity. Heterosexuality has mostly been viewed as the normative and most socially dominant form of sexual orientation.

Bisexuality is romantic attraction, sexual attraction, or sexual behavior toward both males and females. It may also be defined as the attraction to more than one gender, to people of both the same and different gender, or the attraction to people regardless of their sex or gender identity (pansexuality).

The term bisexuality is mainly used for people who experience both heterosexual and homosexual attraction. Bisexuality is one of the three main classifications of sexual orientation along with heterosexuality and homosexuality, all of which exist on the heterosexual–homosexual continuum. A bisexual identity does not necessarily equate to equal sexual attraction to both sexes; commonly, people who have a distinct but not exclusive sexual preference for one sex over the other also identify themselves as bisexual.

Homosexuality is romantic attraction, sexual attraction, or sexual behavior between people of the same sex or gender. It also denotes identity based on attraction, related behavior, and community affiliation.

Along with bisexuality and heterosexuality, homosexuality is one of the three main categories of sexual orientation within the heterosexual–homosexual continuum. Although no single theory on the cause of sexual orientation has yet gained widespread support, scientists favor biological theories. There is considerably more evidence supporting nonsocial, biological causes of sexual orientation than social ones, especially for males. A major hypothesis implicates the prenatal environment, specifically the organizational effects of hormones on the fetal brain. There is no substantive evidence which suggests parenting or early childhood experiences play a role in developing a sexual orientation. Scientific research shows that homosexuality is a natural and normal variation in human sexuality and is not in and of itself a source of negative psychological effects. Major mental health organizations overwhelmingly reject conversion therapy as ineffective, scientifically unsupported and potentially harmful.