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Chapter 2 (continued)
Biologic Theories (cont.)
Hormonal Studies
The hypothesis of studies suggesting that prenatal hormonal factors contribute to homosexuality is based on the fact that, in the womb, the brains of mammals begin “female” and must be exposed to androgens in order to become masculinized.3(p230) Thus it is hypothesized that males were not exposed to sufficient levels of androgens during pregnancy, causing their brains to remain “feminine.”4(p216) Evidence supporting this hypothesis is derived from studies performed on rodents. Researchers were able to produce female sexual behavior (assuming a position receptive to mounting) in male rats that had been deprived of androgens as fetuses; and male sexual behavior (mounting) was produced in female rats exposed to androgens as fetuses5(p315) Byne and Parsons point out that these studies have limited application to human sexuality. The first limitation they point out is that, in these studies, a rat was labeled “homosexual” due to the display of sexual behavior typical of the opposite-gender (males assuming a receptive position, females mounting) and not due to any manifested attraction to same-sex partners. No evidence is provided by these studies to show that artificially hormonalized rats prefer same-gender sex partners. In humans, homosexuality is defined by one’s sexual fantasies and the preferred gender of sexual partners as well as by behavior.3(p231)
The other main limitation pointed out by Byne and Parsons is that sexual behaviors in rodents are very simple and are subject to rigid neuroendocrine control. Humans are far more complex organisms, and it is unlikely that our sexual behavior is fully controlled by endocrine activity. Evidence provided by studies of rodents may be suggestive, but hardly explains the diversity of human sexual behavior.3(p231)
Researchers Anke Ehrhardt and Heino Meyer-Bahlburg of the New York State Psychiatric Institute reviewed the scientific literature regarding the effects of hormones on gender-related behavior in humans and sub-human species. They reported findings in four areas: gender identity, gender-typical activities, sexual orientation, and mental abilities. Their conclusions are as follows. Gender identity, which they define as one’s primary identification with one sex or the other, “depends largely on POSTNATAL environmental influences.” Gender-typical activities, which they describe as “all those aspects of behavior in which normal boys and girls differ from one another,” “appear to be modified by prenatal sex hormones.” Gender-specific mental abilities do not seem to be affected by prenatal hormones. And finally, regarding sexual orientation they state: “we have to assume that prenatal hormone conditions by themselves do not rigidly determine sexual orientation.”6(p1316-1317)
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POSTNATAL: following birth.