In 1990 D F Swaab conducted an experiment which documented the physiological difference in the anatomical structure of a gay man’s brain. He found post-mortem that a portion of the hypothalamus, the portion of the brain directly related to sexual drive and function, was structurally different to that in a heterosexual brain.
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This portion of the hypothalamus was found to be twice the size of its heterosexual counterpart. At the same time another scientist, Laura S Allen made a similar discovery and found that the anterior commissure of the hypothalamus was also significantly larger in homosexuals. These results became the basis of the argument for biological cause of homosexuality.
Simon Levay, a neuroscientist with the Salk Institute of La Jolla, California conducted another experiment of the hypothalamus of the brain in 1991. However, his examinations were on patients who died of AIDS related illnesses, a group including homosexual men, heterosexual men and heterosexual women. He discovered that the third interstitial notch of the hypothalamus was two to three times smaller in the homosexual men, and that the women also displayed this. He concluded that “homosexual and heterosexual men differ in the central neuronal mechanisms that control sexual behaviour”. However the question to be asked was were the sexual practices the cause of the different sizes, not the other way round?
Twin studies have also been used to prove the biological argument. Ernest Kallman conducted the first twin study, finding 100% concordance with monozygotic (identical) twins and only 12% concordance for dizygotic (fraternal) twins. His findings were discredited through methodological problems but his findings paved the way for further experiments and J Michael Bailey and Richard Pillard continued this work. They found that 52% of monozygotic twins were both homosexuals, 22% of dizygotic twins were so and only 5% of non-related adopted brothers. The conclusion was that the more closely genetically linked the more likely they both are to exhibit gay or straight tendencies. But had enough been done to allow for the environment in which the twins were raised? One could argue that 48% of monozygotic twins were not both gay.
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In 1993 Dean Hamer claimed discovery of the “gay gene”. He found that gay brothers shared a specific region of the x chromosome, passed from mother to son, called Xq28, at a higher rate than gay men shared with their straight brothers. (Figure 1).
Figure 1
Hypothetical placement of the "gay gene," on the X chromosome. .
Hamer chose 40 pairs of homosexual brothers and found that 33 of them shared a set of five markers on the long arm of the X chromosome. In the July 19, 1993 edition of Science, Hamer reported that the linkage translated to a “99.5% certainty that there is a gene (or genes) in this area of the X chromosome that predisposes a male to become a heterosexual” (, 1993).
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The clear cause of sexual orientation research has shifted to biological causes and in just the last few months scientists in Vienna announced that they had isolated a master genetic switch for sexual orientation in the fruit fly; once ‘flicked’ the genetically altered males ignored overtures from the females and instead attempted to mate with other males!
**(Gene paragraph here)
Some claim that a specific gene causing homosexuality is unlikely as homosexuals cannot reproduce amongst themselves. But it is not uncommon for homosexual men to father children for many reasons; some attempt to overcome their homosexuality and produce offspring, other simply want to be fathers and bear children bcause of the desire to reproduce. Homosexuality does not prohibit a person from being an excellent parent.
Another issue relative to a physiological cause is hormones which control and stimulate various functions of the body. There is speculation that a difference in hormones could be the cause for an erotic attraction to the same gender. However, research claims that the hormaones in the adult appear to “simply impact the intensity of sexuality rather than orientation” (Blumefeld, Raymond 1998).
With the exception of a small group of religious institutions, who generally believe that God opposes homosexuality and that it is caused by environment, the vast majority of human sexuality researchers and mental health therapists accept that the root cause of homosexual orientation is genetic. But some are not convinced and propose that homosexuality is the result of environmental factors, the ‘nurture’ concept.
The Nurture Concept
The nuture concept puts forward the argument that social, parental and environmental factors influence a person’s sexuality. A nutured gay person is one that is ‘made’ gay.
The nuture concept implies that people have a choice whether to be gay or not. The notions of overbearing mothers or absent fathers and even sexual abuse are thought to be the catalyst for ‘future’ gay people.
Sigmund Freud ( ) believed that homosexual men were fixated with their mothers and flet that sexual relations with other men allowed them to remain ‘true’ to their mothers. After Freud many of his followers developed theories of a fixation on the penis as a cause of homosexuality, that a person without a penis was viewed as a non-sexual person.
Psychologist John Watson, renowned for his early experiments with a young orphan called Albert, carried out research which demonstrated that conditioning could produce any phobia. “Give me a dozen healthy infants, well-formed and my own specified world to bring them up in and I’ll guarantee to take any one at random and train him to become any type of specialit I might select…regardless of his talents, penchants, tendencies, abilities, vocations and race (Watson 2002).
B F Skinner, a Harvard psychologist, is known as the father of behavioural science and proved with experiments involving teaching pigeons to dance and play tennis that human behaviour could be conditioned in the same way as animals.
Behaviourists believe that sexual and gender identification result from roles imposed by family and peers, such as masculine and feminine stereotypical roles.
Two predominant theorists on homosexuality are david halperin and Jean Foucault. Both have largely contrasting ideas on the environmental contributions to formation of homosexuality. Halperin, a Freudian psychologist believes that homosexuality is a freak of nature, derived from a failure to resolve Oedipal issues (a dominant mother figure) and argues that this combined with a weak or absent father will lead to a weak, homosexual son. Opponents would say that this could also lead to a stronger son, compensating for his father’s weaknesses.
Jean Foucault theorises that homosexuality appeared as one of the forms of sexuality only created “because we made it so”; that homosexuals were aberrations which had then become a ‘species’, the depth of desire being superficial. Halperin contrasts this by saying that homosexuality does go deeper and is a psychological condition with much deeper roots.
Various other studies have presented excessive masturbation, an accidental homosexual encounter, a missing or uncaring father, an unfulfilling first heterosexual experience, dominant mothers and poor role models all as causes of homosexuality. Many religious institution believe that if homosexuality is a choice then individuals can change their orientation through ‘reparative therapy’ although this has been proven to have a near zero success rate. (Bell,1996)
**ADD conclusions of the religious groups in here)
Thomas Schmidt, author of “Straight and narrow? Compassion and Clarity in the homosexual debate” (1998) takes this religious stance and argues that a parent influences his or her childs eventual sexual preference. Basically he believes homosexuality is a choice and a morally wrong one, perpetuated by a persons decision to act on it. An advocate of the Christian therapy for homosexuality he argues that no research has actually proved a genetic association to homosexuality.
Conclusion
Researchers on all sides of the debate agree that the link between a gene and a behaviour is not the same as cause and effect. A gene may increase the likelihood of a behaviour but it does not make people do things, which ultimately means that we still get to choose who we will be.
**Add Bem’s theories and table
Guilt is perhaps one of the greatest reasons for the born or made debate. If born a homosexual then guilt is removed as it can be reduced to an issue such as the colour of ones hair or eyes. Others insist homosexuals make a lifestyle choice and that the heterosexual majority could then condemn the homosexual minority.
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**Add penguin story
Whatever your personal opinion the accumulating biological evidence is having an effect. In February Reverand Rob Schenck, a prominent evangelical leader in Washington DC stated that he believes homosexuality is not a choice but rather a disposition and that this conversion came about after he had spoken to genetic researchers and counsellors.
His message? “If it is inevitable that this scientific evidence is coming we have to be prepared with a loving response. If we do not have one we will not have any credibility”
Although an interesting debate it seems that no one theory or experiment gives a definitive answer
