Homosexuality in Western popular thought over the course of the 20th century has generally referred to sexual acts between individuals of the same sex. There has been and continues to be a common belief that individuals are either homosexual or heterosexual, both in terms of their sexual orientation and behavior.

In reality, many individuals engage in a wide spectrum of sexual behaviors at any given stage in their lives or over the course of their lives. While there are individuals who at any given point in time may engage in exclusively other-sex or same-sex sexual behaviors, others may exhibit a pattern of "bisexuality" that involves varying degrees of both other-sex or same-sex behavior.

Furthermore, an individual who at one point in his or her lifetime engages exclusively or primarily in other-sex behavior may opt to engage exclusively or primarily in same-sex behavior, or vice versa at a later point in time.

The Famous Kinsey Studies
In his now classic studies on male and female sexuality in U.S. society, published respectively in 1948 and 1953, Alfred C. Kinsey, a prominent pioneer in sexual research, argued that humans cannot be easily put into invented categories such as "heterosexual" and "homosexual."

Somewhat later, Michel Foucault, a prominent French philosopher and psychologist, argued that the category "homosexual" is a social construct that is only a little over 100 years old.

Indeed, not until 1926 was the term first seen in print, in the New York Times. Foucalt asserted that the practice of sodomy became transformed into an explicit social category referred to as homosexuality. This term has been interpreted in a wide variety of ways, ranging from a form of psychodynamic pathology to an alternative sexual lifestyle engaged in by sensitive and enlightened individuals who often refer to themselves as gays or lesbians.

No Homosexuality in Ancient Greece
According to this social constructivist perspective, homosexuality per se did not exist in ancient Greece or various other indigenous societies in which same-sex behaviors of one sort or another reportedly occurred.

Indeed, the ancient Greeks did not even have an equivalent for the terms "homosexual" or "heterosexual," although same-sex sexual behavior was not only practiced but extolled. At any rate, same-sex behaviors include oral-genital intercourse, anal intercourse, insertion of dildoes, mutual masturbation, hugging, kissing, stroking, and various other activities. To a large extent, same-sex oriented people engage in many of the same forms of sexuality as do other-sex oriented people.

Until recently, most theorists and therapists tended to view homosexuality as a deviant or aberrant form of behavior—a view still widely held by the general public and by certain religious groups.

Cross-cultural evidence demonstrates that same-sex behavior in many societies may be regarded as different but not morally defective or psychologically abnormal.

Socially-Institutionalized Homosexuality
Indeed, various indigenous groups, such as the Sambia on the island of New Guinea, actually have a form of socially-institutionalized and approved form of homosexuality in which adolescent males engage in same-sex acts, such as fellatio, before marrying a woman and rearing a family. Some males may choose to restrict their behavior to same-sex acts after adolescence and some married males may occasionally engage in same-sex acts.

By contrast, Western psychology and psychiatry, at least until relatively recently, have tended to regard same-sex behavior as abnormal and the product of inappropriate gender socialization.

Although Freud argued that humans are born with a bisexual nature which in time becomes mediated by culture, the American Psychiatric Association up until 1973 had designated homosexuality as a pathological form of behavior. The Association lifted its claim that homosexuality is abnormal in 1974, and now maintains that there is no scientific evidence that demonstrates the effectiveness of any therapies that attempt to transform homosexuals into heterosexuals.

In 1994, the American Medical Association, a traditionally conservative organization, called for "a non-judgmental recognition of sexual orientation by physicians."

Causes of Same-Sex Orientation Controversial
While the evidence still remains highly tentative, there is cause to believe that some individuals exhibit a greater biopsychological predisposition to engage in same-sex acts than others.

A team of National Cancer Institute researchers in a study of over 100 homosexual men found that many of their uncles and male cousins were also homosexual, suggesting an hereditary factor. In its comparison of the DNA of 40 pairs of same-sex oriented brothers, it was learned that almost all shared genetic markers in the Xq28 region of the X chromosome. Research on the DNA of 36 lesbian sisters did not reveal a corresponding pattern.

People who prefer to engage in same-sex behavior vary widely in terms of their lifestyles. While many continue to remain circumspect and even secretive about their sexual orientation for a variety of reasons, others have chosen to "come out of the closet" and participate in the gay and lesbian subcultures which have become more visible and politically active both domestically and internationally.

A Maturation Process
Despite a growing understanding of the nature of homosexuality, myths about people who prefer to engage in same-sex behavior continue to abound. Contrary to the common belief that homosexuals tend to recruit children and unsuspecting adults into same-sex behavior, homosexuals, like heterosexuals, discover their sexuality as a process of maturation.

The vast majority of individuals who engage in same-sex behavior are reared in heterosexual homes. Due to the pervasive patterns of homophobia or anti-homosexual sentiments and behaviors that exist in the larger society, many same-sex oriented individuals experience considerable psychic ambivalence and even distress in the process of coming to terms with their sexuality.

Teens exhibiting a same-sex orientation are reportedly three times more likely than their other-sex oriented peers to attempt suicide. Homophobia also causes a high level of violence and discrimination targeted at gays and lesbians, and disproportionate rates of alcoholism and other substance abuse among gays and lesbians. Contrary to popular stereotypes, few homosexuals in the U.S. can be characterized as assuming only a masculine or only a feminine role in sex.

Research suggests that homosexual behavior tends to fall into the following three categories in terms of frequency:

oral-genital acts, hugging, and kissing
anal sex
alternative acts such as "fisting" (in which a hand, but not in the form of a fist, is inserted into the partner's rectum).
Although homosexuality is often popularly associated with transvestitism or cross-dressing, heterosexual cross-dressers appear to be about as common as homosexual cross-dressers. Furthermore, homosexual men do not appear to be any more prone to pedophilia (sexual attraction to children) than do heterosexual men.

Various surveys indicate that homosexuals have more partners over the course of their lifetimes than do heterosexual or "straight" individuals. Nonetheless, many homosexuals form long-term, monogamous relationships.

Indeed, the AIDS epidemic has prompted many homosexuals to choose a lifestyle emphasizing an exclusive sexual relationship with a single partner rather than one emphasizing multiple-partner relationships.

Female Homosexuality
Cross-culturally, women appear to participate in same-sex relationships less often than men. Same-sex relations among women, however, tend to be more acceptable in certain indigenous communities and Third World countries.

In some African communities, prosperous trader women may choose to marry women and even establish families with them by having a son or trusted male employee impregnate their wives.

In India, some homosexual women have a socially approved role as devotees of certain Hindu or Sikh goddesses.

Despite the existence of female homosexuality in all societies both today and in the past, women who engage in same-sex practices have tended to be ignored in Western historical studies. The recent renaissance of gay and lesbian studies has played an important role in changing awareness of homosexuality.