The term heterosexual refers to an inclusive sexual attraction towards the other sex, that is, women only feel attracted to men and men only to women. Current studies document that 95% of all people identify themselves as heterosexual. [1] [2]

This form of sexual orientation is also regarded as social norm. Due to older traditions, social influence or depictions in media like film, television, music and internet this concept often is internalized. The main argument of those in favour of a heteronormative system is that only heterosexual sex can conceive children and thus only heterosexuality is regarded "normal" and "natural". By implication, all other forms of sexuality are a departure from the norm. Queer theory criticizes this stance and calls for questioning heteronormativity. [3]

The sexologist Alfred Kinsey already dealt with the question if heterosexuality was so prevalent at mid-twentieth century. His published scale served as the assessment of people's sexual orientation. The Kinsey Scale ranges from heterosexual (0) to exclusively homosexual (6) and 1-5 for varying levels of desire or sexual activity with either sex. What's special about it is that not only experienced sexuality but also fantasies and wishful thinking are parrt of the parameter. The category X stands for asexual people who are neither attracted to men nor women. [4] The scientific results were published in two books called the Kinsey Report. They played an important role in sexual revolution due to the removal of sexual taboos. [5] [6]

"It is a characteristic of the human mind that tries to dichotomize in its classification of phenomena....Sexual behavior is either normal or abnormal, socially acceptable or unacceptable, heterosexual or homosexual; and many persons do not want to believe that there are gradations in these matters from one to the other extreme. [4]
(American sexologist and professor for zoology at Indiana Unversity, Alfred Charles Kinsey, 1953)

Further Links:
Kinsey, Bill Condon, 2004 (Trailer)
The Inner Circle, T. C. Boyle, 2004 (Novel)