Most sexual reproduction in the animal world is facilitated through opposite-sex sexual activity, although there are also animals that reproduce asexually , including protozoa and lower invertebrates. Kinsey Reports Intimate heterosexual couple At the beginning of the 20th century, early theoretical discussions in the field of psychoanalysis posited original bisexuality in human psychological development. Quantitative studies by Alfred Kinsey in the s and Dr. Fritz Klein 's sexual orientation grid in the s find distributions similar to those postulated by their predecessors.
According to Sexual Behavior in the Human Male by Alfred Kinsey and several other modern studies, the majority of humans have had both heterosexual and homosexual experiences or sensations and are bisexual. Kinsey himself, along with current sex therapists, focused on the historicity and fluidity of sexual orientation. Kinsey's studies consistently found sexual orientation to be something that evolves in many directions over a person's lifetime; rarely, but not necessarily, including forming attractions to a new sex.
Rarely do individuals radically reorient their sexualities rapidly—and still less do they do so volitionally—but often sexualities expand, shift, and absorb new elements over decades.
For example, socially normative "age-appropriate" sexuality requires a shifting object of attraction especially in the passage through adolescence. Contemporary queer theory , incorporating many ideas from social constructionism , tends to look at sexuality as something that has meaning only within a given historical framework. Sexuality, then, is seen as a participation in a larger social discourse and, though in some sense fluid, not as something strictly determinable by the individual.
Other studies have disputed Kinsey's methodology. For example, people may state different sexual orientations depending on whether their immediate social environment is public or private. Reluctance to disclose one's actual sexual orientation is often referred to as "being in the closet. Nature and nurture[ edit ] The considerable " nature and nurture " debate exists over whether predominantly biological or psychological factors produce sexual orientation in humans, or whether both significantly factor into sexual orientation.
Candidate factors include genes , the exposure of fetuses to certain hormones or lack thereof and environmental factors. Critique of studies[ edit ] The studies performed in order to find the origin of sexual orientation have been criticized for being too limited in scope, mostly for focusing only on heterosexuality and homosexuality as two diametrically opposite poles with no orientation in between.
It is also asserted that scientific studies focus too much on the search for a biological explanation for sexual orientation, and not enough on the combined effects of both biology and psychology. Yet just like intelligence, sexuality is a complex human feature that modern science is attempting to explain with genetics.
Research on brain size, hormone levels, finger length, and other biological traits have yet to yield evidence for this, however. It is important to note that traits such as these result from a combination of gene expression and developmental and other environmental factors. Rather than determining that this results from purely biological processes, a trait evolves from developmental processes that include both biological and social elements.
Sexual orientation identity and Sexual fluidity Often, sexual orientation and sexual orientation identity are not distinguished, which can impact accurately assessing sexual identity and whether or not sexual orientation is able to change; sexual orientation identity can change throughout an individual's life, and may or may not align with biological sex, sexual behavior or actual sexual orientation.
For men, a change occurred in 0. For women, a change occurred in 1. The researchers suggested that heterosexuality may be a more stable identity because of its normative status.
Diamond on a sample of 80 non-heterosexual female adolescents age reported that half of the participants had changed sexual-minority identities more than once, one third of them during the 2-year follow-up. Diamond concluded that "although sexual attractions appear fairly stable, sexual identities and behaviors are more fluid. Among the male subjects, however, the straight men were more turned on by erotic films with women, the gay ones more by those with men.
The study's senior researcher said that women's sexual desire is less rigidly directed toward a particular sex, as compared with men's, and it is more changeable over time. It has been characterized as "mostly straight". Sexual orientation change efforts Sexual orientation change efforts are methods that aim to change sexual orientation, used to try to convert homosexual and bisexual people to heterosexuality. Scientists and mental health professionals generally do not believe that sexual orientation is a choice.
Those efforts have been controversial due to tensions between the values held by some faith-based organizations, on the one hand, and those held by LGBT rights organizations and professional and scientific organizations and other faith-based organizations, on the other. While opposing conversion therapy, they encourage gay affirmative psychotherapy  and "encourages mental health professionals to avoid misrepresenting the efficacy of sexual orientation change efforts by promoting or promising change in sexual orientation when providing assistance to individuals distressed by their own or others' sexual orientation and concludes that the benefits reported by participants in sexual orientation change efforts can be gained through approaches that do not attempt to change sexual orientation".
Human mating strategies An intimate heterosexual couple Since the s and s, a large body of research has provided evidence and analysis of the extent to which heterosexuality and homosexuality are socially organized and historically changing. A heterosexual couple, a man and woman in an intimate relationship , form the core of a nuclear family. In some jurisdictions, when an unmarried man and woman live together long enough, they are deemed to have established a common-law marriage.
Social history and terminology[ edit ] There was no real need to coin a term such as "heterosexual" until there was something else to contrast and compare it with. The Victorian work ethic had changed, pleasure became more highly valued and this allowed ideas of human sexuality to change.
Consumer culture had created a market for the erotic, pleasure became commoditized. At the same time medical doctors began to acquire more power and influence. The basic oppositeness of the sexes was the basis for normal, healthy sexual attraction. Heteronormativity and heterosexism[ edit ] See also: It can assign strict gender roles to males and females. The term was popularized by Michael Warner in Heterosexuality is then viewed as the natural inclination or obligation by both sexes.
Consequently, anyone who differs from the normalcy of heterosexuality is deemed deviant or abhorrent. It may include an assumption that everyone is heterosexual and may involve a varied level of discrimination against gays, lesbians, bisexuals, heteroflexibles , or transgender individuals. Straight pride is a slogan that arose in the late s and early s and has been used primarily by social conservative groups as a political stance and strategy.