Is there evidence that life experiences play a role in sexual orientation? The identical twins were far more similar than the fraternal twins. The results were that they were more alike. And the theory is if a particular trait is genetic, the identical twins would be more alike than the fraternal twins. What we did was to recruit groups of twins, identical and fraternal twins. It’s one of the great mysteries of science, at least of biological science.Ĭan you talk about the twin research you’ve conducted? But nobody knows for sure what causes a person to be either gay or straight. The talk is part of the OUTlook Lecture series, sponsored by the LGBTQ ministry at Marsh Chapel.īU Today: Has your research found that sexual orientation is biologically determined? “I think some sort of genetic influence seems very likely, but beyond that, what really can we say? And the answer is: not a lot.”īU Today caught up with Pillard to talk about the lecture he will deliver tonight, titled Born This Way: The Biology of Sexual Orientation. “It’s really hard to come up with any definite statement about the situation,” he says. Pillard is quick to point out that much about how sexual orientation is determined remains a mystery. Pillard and Bailey’s findings have been debated in the intervening decades. They found that if one identical twin was gay, 52 percent of the time the other was also the figure was 22 percent for fraternal twins, and only 5 percent for nonrelated adopted brothers. Pillard and Bailey examined identical and fraternal twin brothers-as well as nonrelated brothers who had been adopted-in an effort to see if there was a genetic explanation for homosexuality. In their findings, published in the Archives of General Psychiatry, they argued that decades of psychiatric research into social and cultural causes show “small effect size and are causally ambiguous.” Michael Bailey, a professor of psychology at Northwestern University, conducted in the early 1990s that found that homosexuality is largely biologically determined, not environmentally influenced.
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Among the most notable were a series of studies Pillard and J. There have been numerous studies designed to determine whether or not homosexuality has a genetic cause.
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In 1973, based on Hooker’s findings, the American Psychiatric Association removed homosexuality from its Diagnostic and Statistical Manual of Psychological Disorders and in 1975, released a public statement that homosexuality was not a mental disorder. Because of the similar scores, she concluded that sexuality is not based on environmental factors. Hooker found no major differences in the answers given by the two groups. The subjects were then given three psychological tests: the Rorschach, the Thematic Apperception Test (TAT), and the Make-a-Picture-Story Test (MAPS). Hooker studied both homosexuals and heterosexuals-matched for age, intelligence, and education level. With a grant from the National Institute of Mental Health, Karen Hooker studied the relationship between homosexuality and psychological development and illness. The first psychological test undertaken to determine whether there was a biological explanation for homosexuality was in 1957.
At the time, the American Psychological Association still listed homosexuality as a disorder and psychologists and psychiatrists were trained on ways to treat it. It was the 1950s and the School of Medicine professor of psychiatry was at the University of Rochester. Homosexuality was considered a mental illness when Richard Pillard was in medical school. “I think some sort of genetic influence seems very likely,” he says, “but beyond that, what really can we say? And the answer is: not a lot.” Twitter Facebook Richard Pillard says that much about how sexual orientation is determined remains a mystery.