This is the 2007 version. Click here for the 2017 chapter 16 table of contents.

What Causes Homosexuality?

Is homosexuality learned, or is it the product of certain childrearing practices, or are homosexuals "born that way"? Evidence points to the latter conclusion.

What are some reasons for thinking homosexuals are "born that way"?

First, there is the evidence cited earlier that children who become homosexual are different from an early age.

Second, there is the ease with which homosexual behavior can be produced in non-human animals by manipulating sex hormones.

Third, there is the discovery that male homosexuals have brain areas and biological responses to sexual stimuli that resemble those of heterosexual females more than those of heterosexual males.

Fourth, there is evidence from a variety of sources pointing to genetic influences on homosexuality.

What are some findings regarding genetic influences on homosexuality?

One group of researchers studied identical twins and found that, of 56 sets of identical twins in which one member was gay, the other twin was also gay in 52 percent of the cases. That means that nearly half the identical twins of gay men were not gay, so it suggests a strong but not determinative genetic component (Adler, 1992) In Thomas Bouchard's study of identical twins separated at birth, there were three pairs of male identical twins in which at least one was homosexual. In two out of three cases, the other twin was homosexual also, despite being raised in a different household and never seeing his twin brother during childhood.

How do male and female homosexuals differ in their perception of choice?

Male and female homosexuals differ somewhat in their perception of free choice regarding homosexuality. Most male homosexuals trace their feelings to childhood and believe they have no choice in the matter of sexual orientation. However, in one study over 50% of lesbians said their sexual orientation was a "free choice." Only 20% viewed lesbianism as an innately determined orientation (Knox, 1984).

What are some possible explanations for the difference between male and female homosexuals in perceived freedom of choice?

What accounts for this difference? Perhaps lesbianism is not as likely to be determined genetically as male homosexuality. "Researchers concluded that for males, homosexuality is about 50% heritable. The figure is substantially lower in females" (Holden, 1995).

Knox (1984) raised another possibility. Lesbians are more likely to feel they have a free choice because lesbians are physically able to have sex with a man. Many discover their lesbianism in the context of a failed marriage or troubled heterosexual relationship. The decision to concentrate on lesbian relationships may be a conscious one, made at a certain time, as a free choice. By contrast, some male homosexuals are physically unable to have sex with a woman, unless they fantasize about a man. In such a case, a man is likely to feel he is naturally homosexual.

What is "the most important thing" in defining homosexual experience? How do many gays and lesbians prefer to define homosexuality?

An important point to raise in this discussion is that the sex act is not necessarily the most important thing that defines the gay and lesbian experience. Indeed, many gays and lesbians object to the "genitalizing" of homosexuality. Homosexuality is not just about sex, any more than heterosexual relationships are just about sex. Intensity of emotional response is the most important thing, some homosexual people insist. Gay men often remember "crushes" on other men, early in adolescence before sexual activity. Lesbian women report similar attachments. For many homosexuals, the best definition of homosexuality is one that does not involve sex. They suggest that homosexuality is simply a strong tendency to fall in love with members of the same sex.

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