A second folk theory based upon modeling holds that boys grow up to be gay if their fathers are weak and ineffectual. Such a theory equates homosexuality with inadequacy, a dubious identification. Moreover, it ignores the fact that more than half of marriages end in divorce and a substantial number of children grow up without a father in the house. There is not a shred of evidence that sexual orientation is influenced either by divorce (no matter how bitter) or by the absence of the father.
Still another folk theory holds that gay men are afraid of women. This idea is sometimes called the vagina dentata theory; it is based upon the notion that a gay man hates his mother, and transfers that hate to all other women. Needless to say, there is no better support for this folk theory than for the others, and it ignores the fact that many gay men have had, and will continue to have, satisfying sexual experiences with women.
The first person to propose a biological theory for the origin of homosexuality was the philosopher Aristotle. He wondered why some men liked to get fucked. In explanation, he suggested that such people had an extra nerve that ran to the rectum, which, he hypothesized, was stimulated during intercourse. Though ingenious, Aristotle's extra-nerve theory doesn't hold up anatomically.
A nineteenth-century French doctor, A. Tardieu, claimed that the active pederast had a slender, underdeveloped penis tapered like a dog's, and that those assuming the "passive" role in anal intercourse had smooth rectums. One wonders how anyone could come up with anything so preposterous.
A number of biological theories were proposed throughout the twentieth century to explain homosexuality. The simplest was genetic: Homosexuality is inherited. This is hotly debated.
The next biological theory was based upon hormone levels. Simple-minded psychologists and psychiatrists suggested that gay men had excessive female hormones (estrogens) circulating in their bodies, but were deficient in male hormones (androgens). After decades of research the theory was found to be completely in error. There are no demonstrable hormonal differences between persons with different sexual orientations.
The most recent biological theory holds that sexual orientation is determined in the brain of the fetus during the fourth to seventh month of pregnancy. Devotees of this prenatal theory suggest that the brain develops as either male or female. They say an "abnormality" may cause the male fetus's brain to develop into a female brain and that such a boy is destined to become an adult homosexual. Conversely, a male brain in a female is said to produce an adult lesbian.
The prenatal theory, like the others, has foundered on the rock of hard evidence. However, research in endocrinology may one day reveal the secret of sexual orientation. For the moment, biological explanations of homosexuality remain hotly contested. Recent anatomical studies have suggested differences between male and female brains, and between the brains of gay and straight men. How the data from anatomical studies will fit in with that from prenatal hormonal research remains to be seen.
There have been just as many psychological theories. The first (and the quaintest) we know of was suggested by a Persian physician a few hundred years ago. He wondered why so many Persian men preferred to have anal intercourse with young boys rather than vaginal intercourse with their wives. He believed that preference for vaginal or anal intercourse was determined by how a man learned to masturbate. He said men were either "pounders" or "flippers." Pounders held their dicks very tightly and in adulthood preferred the tightness of a boy's asshole, while flippers held their dicks loosely and therefore enjoyed the wideness of a woman's vagina. While obviously incorrect about the origin of sexual orientation, the theory allows us a small window through which to view a past society that was more positive than our own about both masturbation and anal intercourse.
Of the twentieth-century psychological theories, the most discussed are those of Freud and his successors. Describing what he called the Oedipus complex, Freud wrote that a boy of four or five wants to have sex with his mother. The boy is afraid, according the Freud, that the father will discover this incestuous wish and castrate him. To defend himself, the boy either identifies with his father, becomes heterosexual, and thereby enjoys a vicarious sexual relationship with his mother, or he identifies with his mother and becomes homosexual.
Later psychoanalysts rejected Freud's theory, which was based on the belief that everyone is born bisexual and is potentially either heterosexual or homosexual. These sexist psychoanalysts were uncomfortable with the notion of bisexuality and proposed, instead, that boys are turned into homosexuals by "castrating" or "engulfing" mothers, women who are seductive toward their sons. Neither Freud's theory nor the later revisionist theory has the least bit of scientific evidence to support it, although this hasn't stopped the vast majority of psychoanalysts from trying to "cure" their homosexual patients.
By this point, it should be clear that there is no generally accepted theory to explain the origin of homosexuality. Researchers are still split between those who uphold either a psychological or a biological explanation. But is there any reasons to "explain" the origins of homosexuality? Noticeably absent is any research into the etiology of heterosexuality. (Read Homosexual Behavior: A Modern Reappraisal by Judd Mainor and Homosexuality: Research Implications for Public Ploicy by John Gonsiorek and James Weinrich.)
Whenever society, through its medical authorities, has tried to "eplain" homosexuality, such explanations have been merely pretexts for attempts to "cure" it. The cures have included castration, electric and chemical shock, imprisonment, and ostracism. Who can blame gays for being skeptical of the motives of straight authorities investigating the "etiology" of homosexuality? Don't let anyone try to change your sexual orientation. It's as natural as your need for food and drink. (Read Cures by Martin Duberman.)