Sexual orientation

Sexual orientation refers to the direction of an individual's sexuality, usually conceived of as classifiable according to the sex or gender of the persons whom the individual finds sexually attractive. The most commonly used categories of sexual orientation are heterosexuality (being sexually attracted to members of the opposite sex), homosexuality (being sexually attracted to members of the same sex) and bisexuality (being sexually attracted to members of either sex).

Most definitions of sexual orientation include a psychological component (such as the direction of an individual's erotic desire) and/or a behavioural component (which focuses on the sex of the individual's sexual partner/s). Some prefer simply to follow an individual's self-definition or identity.

More recently, scholars of sexology, anthropology and history have argued that social categories such as heterosexual and homosexual are not universal. Different societies may consider other criteria to be more significant than sex, including the respective age of the partners, the sexual role played by each partner (such as active or passive), or the social status of the partners.

Sexual identity may be used as a synonym for sexual orientation, but the two are also sometimes distinguished, with identity referring to an individual's conception of themselves, and orientation referring to "fantasies, attachments and longings" and/or behavior. In addition, sexual identity is sometimes used to describe a person's perception of his or her own sex, rather than sexual orientation. The term sexual preference has a similar meaning to sexual orientation, but is more commonly used outside of scientific circles by people who believe that sexual orientation is, in whole or part, a matter of choice.

Measuring an individual's sexual orientation
Varying definitions and strong social norms about sexuality can make sexual orientation difficult to quantify. Researchers may use different markers of sexual orientation, including self-labeling, sexual behaviour, sexual fantasy or a pattern of erotic arousal. A clinical measurement may use penile or vaginal photoplethysmography, where genital engorgement with blood is measured in response to exposure to different erotic material. In 1995, two researchers argued that due to a lack of research on change over time, there is a limitation on current conceptualizations of sexual orientation. They did not abandon the concept of sexual orientation, but concluded that "given such significant measurement problems, one could conclude there is serious doubt whether sexual orientation is a valid concept at all," and warned against increasing politicization of this area.

From at least the late-19th century in Europe, there was speculation that the range of human sexual response looked more like a continuum than two or three discrete categories. 28-year-old Berlin sexologist Magnus Hirschfeld published a scheme in 1896 that measured the strength of an individual's sexual desire on two independent 10-point scales, A (homosexual) and B (heterosexual). A heterosexual individual may be A0, B5; a homosexual individual may be A5, B0; An asexual would be A0, B0; and someone with an intense attraction to both sexes would be A9, B9.

Fifty years later, American sexologist Alfred Kinsey wrote in Sexual Behavior in the Human Male (1948):

The Kinsey scale measures sexual orientation from 0 (exclusively heterosexual) to 6 (exclusively homosexual), with an additional category, X, for those with no sexual attraction to either women or men. Unlike Hirschfeld's scale, the Kinsey scale is one-dimensional. Simon LeVay writes, "it suggests (although Kinsey did not actually believe this) that every person has the same fixed endowment of sexual energy, which he or she then divides up between same-sex and opposite-sex attraction in a ratio indicative of his or her own sexual orientation."

Malleability of sexual orientation
In his 1985 book The Bisexual Option, Fritz Klein developed a scale to test his theory that sexual orientation is a "dynamic, multi-variable process" — dynamic in that it may change over time, and multi-variable in that it is composed of various elements, both sexual and non-sexual. Klein took into account sexual attraction, sexual behavior, sexual fantasies, emotional and social partners, lifestyle, and self-identification. Each of these variables was measured for the person's past, present, and ideal.

The degree in which sexuality can change varies from person to person. The Centre for Addiction and Mental Health has said "For some people, sexual orientation is continuous and fixed throughout their lives. For others, sexual orientation may be fluid and change over time." Research by Lisa Diamond has shown the sexual orientation is more fluid among bisexual women than lesbians.

Other organizations disagree with Fritz Klein. The American Psychological Association has stated that homosexuality "is not changeable." In 2001, the United States Surgeon General David Satcher issued a report maintaining that "there is no valid scientific evidence that sexual orientation can be changed."

Desire, behavior and identity
Some people distinguish between Mainstream medical organizations have made clear that ”sexual behavior does not necessarily equate to sexual orientation.“
 * 1) opposite/same-sex desires
 * 2) opposite/same-sex sexual activity/behavior
 * 3) attraction to the other's sex (male/female) vs. attraction to the other's perceived gender-characteristics (masculine/feminine)
 * 4) self-identifying as straight, lesbian, gay, etc.

Sexual orientation and gender identity
The earliest writers on sexual orientation usually understood it to be intrinsically linked to the subject's own sex. For example, it was thought that a typical female-bodied person who is attracted to female-bodied persons would have masculine attributes, and vice versa. This understanding was shared by most of the significant theorists of sexual orientation from the mid-19th to early 20th century, such as Karl Heinrich Ulrichs, Richard von Krafft-Ebing, Magnus Hirschfeld, Havelock Ellis, Carl Jung and Sigmund Freud, as well as many gender variant homosexual people themselves. However, this understanding of homosexuality as sexual inversion was disputed at the time, and through the second half of the 20th century, gender identity came to be increasingly seen as a phenomenon distinct from sexual orientation. Transgender and cisgender people may be attracted to men, women, or both, although the prevalence of different sexual orientations is quite different in these two populations (see sexual orientation of transwomen). An individual homosexual, heterosexual or bisexual person may be masculine, feminine, or androgynous, and in addition, many members and supporters of lesbian and gay communities now see the "gender-conforming heterosexual" and the "gender-nonconforming homosexual" as negative stereotypes. However, studies by J Michael Bailey and KJ Zucker have found that a majority of gay men and lesbians report being gender-nonconforming during their childhood years.

The majority of transgender people today identify with the sexual orientation that corresponds with their gender; meaning that a transwoman who is solely attracted to women would often identify as a lesbian. Female-attracted transmen often consider themselves straight men, yet some participate in the lesbian community.

For these reasons, the terms gynephilia and androphilia are occasionally (but increasingly) used when referring to the sexual orientation of transgender and intersex people (and occasionally, cisgender people), because rather than focusing on the sex of the subject, they only describe that of the object of their attraction. The third common term that describes sexual orientation, bisexuality, makes no claim about the subject's sex or gender identity. (See also Pansexuality)

Sexual orientation sees greater intricacy when non-binary understandings of both sex (male, female, or intersex) and gender (man, woman, transgender, third gender, or gender variant) are considered. Sociologist Paula Rodriguez Rust (2000) argues for a more multifaceted definition of sexual orientation:

Demographics of sexual orientation
The multiple aspects of sexual orientation and the boundary-drawing problems already described create methodological challenges for the study of the demographics of sexual orientation. Determining the frequency of various sexual orientations in real-world populations is difficult and controversial.

In the oft-cited and oft-criticized Sexual Behavior in the Human Male (1948) and Sexual Behavior in the Human Female (1953), by Alfred C. Kinsey et al., people were asked to rate themselves on a scale from completely heterosexual to completely homosexual. Kinsey reported that when the individuals' behavior as well as their identity are analyzed, most people appeared to be at least somewhat bisexual - i.e., most people have some attraction to either sex, although usually one sex is preferred. According to Kinsey, only a minority (5-10%) can be considered fully heterosexual or homosexual. Conversely, only an even smaller minority can be considered fully bisexual (with an equal attraction to both sexes).

Kinsey's methods have been criticized as flawed, particularly with regard to the randomness of his sample population, which included a large number of prison inmates. Nevertheless, Paul Gebhard, subsequent director of the Kinsey Institute for Sex Research, reexamined the data in the Kinsey Reports and concluded that accounting for major statistical objections barely affected the results. Most modern scientific surveys find that the majority of people report a mostly heterosexual orientation. However, the relative percentage of the population that reports a homosexual orientation varies with differing methodologies and selection criteria. Most of these statistical findings are in the range of 2.8 to 9% of males, and 1 to 5% of females for the United States — this figure can be as high as 12% for some large cities and as low as 1% percent for rural areas). In gay villages such as The Castro in San Francisco, California, the concentration of self-identified homosexual people can exceed 40%.

Estimates for the percentage of the population that are bisexual vary widely, at least in part due to differing definitions of bisexuality. Some studies only consider a person bisexual if they are nearly equally attracted to both sexes, and others consider a person bisexual if they are at all attracted to the same sex (for otherwise mostly heterosexual persons) or to the opposite sex (for otherwise mostly homosexual persons). A very small percentage of people are not sexually attracted to anyone (asexuality).

Determinants of sexual orientation
The American Academy of Pediatrics has stated "Sexual orientation probably is not determined by any one factor but by a combination of genetic, hormonal, and environmental influences." Considerable debate continues over what biological and/or psychological variables determine sexual orientation in humans, such as genes and the exposure of certain levels of hormones to fetuses. Freud and others in the psychoanalytic tradition speculate that formative childhood experiences help determine sexual orientation.

Genetic
In 1993, Dean Hamer found the genetic marker Xq28 on the X chromosome. Hamer claimed in his study to have found a link between the Xq28 marker and male homosexuality, but the original study's results have been disputed. Flies bearing mutant alleles of the fruitless gene, causes male flies to court and attempt to mate exclusively with other males.

Twin studies indicate that male homosexuality may have a genetic component while at the same time indicating that genes are unlikely to be the only determining factor. One common type of twin study compares the monozygotic (or identical) twins of people possessing a particular trait to the dizygotic (non-identical, or fraternal) twins of people possessing the trait. Bailey and Pillard (1991) in a study of gay twins found that 52% of monozygotic brothers and 22% of the dizygotic twins were concordant for homosexuality. It should be noted that this study, if correct, would rule out the possibility that male homosexuality derives solely from a genetic basis (in which case the monozygotic concordance rate would need to be nearly 100%). Bailey, Dunne and Martin (2000) used the Australian twin registry to obtain a sample of 4,901 twins. The results of their multivariate analyses tend to suggest "significant and moderate genetic and nonshared environmental contributions for sexual orientation and its covariates". With regard to methodology, however, it must be borne in mind that the notion of homosexuality as an objective "trait" can be rather problematic. Various researchers may define, quantify or reduce the "trait" differently (e.g. with regard to acts, habitual practices, fantasies, desires, self-identification, etc.) such that a search for its supposed genetic components lacks an objectively consistent and stable reference-point. In other words, the search for a genotype is complicated by the absence of a clear and concrete phenotype.

Birth order
A recent study found an increased chance of homosexuality in male humans whose mothers previously carried to term many male children. This effect is nullified if the man is left-handed. No similar effect was found in female humans.

Hormonal
The hormonal theory of sexuality holds that, just as exposure to certain hormones plays a role in fetal sex differentiation, such exposure also influences the sexual orientation that emerges later in the adult. Fetal hormones may be seen as the primary determiner of adult sexual orientation, or a co-factor with genes and/or environmental and social conditions.

Innate bisexuality
Innate bisexuality (or predisposition to bisexuality) is a term introduced by Sigmund Freud (based on work by his associate Wilhelm Fliess), that expounds all humans are born bisexual but through psychological development (which includes both external and internal factors) become monosexual while the bisexuality remains in a latent state.

Homosexuality as a mental illness
Homosexuality is no longer regarded as a mental illness by most segments of the psychiatric community. The reasons for this are not, however, strictly scientific but political and philosophical as well. Following significant pressure from homosexual advocacy groups, as well as the emergence of new scientific data from researchers such as Kinsey and Evelyn Hooker, the trustees of the American Psychiatric Association (APA) voted in 1973 to remove homosexuality as a disorder from the Sexual Deviancy section of the Diagnostic and Statistical Manual of Mental Disorders, the DSM-II. (This was a major move with significant effect: the story ran on the front page of most newspapers, and over the following years the other mental health organizations came to the same conclusion. Today, only a minority of doctors regard homosexuality as a mental illness.

A minority of organizations have still not accepted the "mainstream" medical organizations' positions and presuppositions. For example, the United States Department of Defense still lists homosexuality as a mental disorder. Other governments have also claimed that homosexuality is an illness and have used that as a justification for laws limiting homosexuality. Most Western nations do not regard homosexuality as a mental disorder. The World Health Organization also no longer recognizes it as a disorder.

A choice
There is a debate in popular culture about whether people are able to change their sexual orientations at will (this issue is not to be confused with the object-relational psychoanalytic concept of sexual object-choice). Some people believe that any of the many sexual orientations can be chosen and switched between by preference, and such individuals generally assume that sexual orientation is a lifestyle choice.

Sexual orientation as a social construct
Because sexual orientation is complex and multi-dimensional, some academics and researchers (especially in Queer studies) have argued that sexual orientation is a completely historical and social construction. In 1976 the historian Michel Foucault argued that homosexuality as an identity did not exist in the 18th century; that people instead spoke of "sodomy", which referred to sexual acts. Sodomy was a crime that was often ignored but sometimes punished severely (see sodomy law).

He further argued that it was in the 19th century that homosexuality came into existence as practitioners of emerging sciences and arts sought to classify and analyze different forms of sexuality. Finally, Foucault argues that it was this emerging discourse that allowed some to claim homosexuality as a human identity.

Heterosexuality and homosexuality are terms often used in European and American cultures to encompass a person’s entire social identity, which includes self and personality. In Western cultures some people speak meaningfully of gay, lesbian, and bisexual identities and communities. In other cultures, homosexuality and heterosexual labels don’t emphasize an entire social identity or indicate community affiliation based on sexual orientation.

The boundary between friendship and homosexuality
Some historians and researchers argue that the emotional and affectionate activities associated with sexual-orientation words (gay, straight, etc.) change significantly over time and across cultural boundaries. For example, in many English-speaking nations it is assumed that same-sex kissing, particularly between men, is a sign of homosexuality, whereas various types of same-sex kissing are common expressions of friendship in other nations. Also, many modern and historic cultures have formal ceremonies expressing long-term commitment between same-sex friends, even though homosexuality itself is taboo within the culture.