The Science of Sexuality


With new legislation coming into place in California to ban conversion therapies for homosexual minors, James Kelly looks at the science of human sexuality

In California, legislation is about to come into play banning so-called conversion therapies for minors, which aim to ‘cure’ youths of their homosexuality. However, Christian groups such as the Pacific Justice Institute are already challenging this new law, bringing the question of sexuality orientation and its immutability to the fore once more.

The therapies, which rely on behavioural modification, psychoanalysis and in some cases even sex therapy and/or prayer, are based on notions that homosexuality is a disorder resulting for some psychology disturbance.

Such notions were common in early psychology, and were even held as the general consensus up until the early 1960s, supported by myriad studies, studies that have either been shown to lack scientific rigour or have been outmoded by later works.

Keeping with psychology for the moment, as sexuality (in humans at least) was described predominantly through this branch of science up until extremely recently, psychoanalysis and behaviourism offer the best examples of what was prevalent in the early years of sexual orientation studies. It is important to note that much work in this field, but not all, was started with a view to either curing with was already assumed to be a disease or to classifying its pathology.

Freud postulated that family dynamics influence a child’s ultimate sexual orientation. Ideas like the closeness to a mother and distance or absence of a father steering a boy towards homosexuality or hatred of a mother leading to lesbianism were well respected and even developed on in early psychoanalysis. While Freud himself was sceptical of psychoanalytical conversion therapies and believed that some biological factors may be at work, his contemporaries and those that followed were more prone to viewing homosexuality as a disease, and a curable one at that. The idea that gender traits, including sexual orientation, are learned consciously or unconsciously from parents, peers and society in general and that in homosexuality something goes wrong was adapted from behaviourism, and became the mainstay of later supporters of the view that homosexuality was an acquired disorder.

However, not all psychological studies from the time posed homosexuality as a disease, or even as abnormal. In 1957, Evelyn Hooker stated in The Adjustment of the Male Overt Homosexual that “homosexuals were not inherently abnormal and that there was no difference between homosexual and heterosexual men in terms of pathology”. This paper became influential, especially among proponents of gay rights. The general acceptance of the facts that studies assuming homosexuality was a disease were flawed and that conversion therapies produced no change of orientation was in part due to the modern gay rights movement.

In the decades that have followed since the Stonewall Riots, sexual orientation studies have tended less and less to assume homosexuality is a disorder and have put greater focus on the role biology plays in orientation. The current consensus is that sexual orientation is strongly influenced if not completely determined by biological factors such as genes and hormones. Is essence, the view at large has moved from exclusively nurture to predominantly nature.

Biological theories of sexual orientation see it as part of a larger group or cluster of gender traits and have applied various techniques (genetic studies, endocrinological studies, etc) to evaluate where within the cluster homosexuality lies.

Animal studies have offered great insight into the role of genes and sexual orientation. Sexual orientation in the fruit fly, Drosophila, appears to be completely controlled by the Fruitless gene (Fru). Depending on the way Fru is spliced, the way its mRNA is altered before forming protein, a male or female form will be produced. Females engineered to produce the male form of Fru (the protein) will approach, court and attempt to copulate with other females. Males engineered to produce female Fru will not approach females.

In humans things are a little more complicated, and altering gene expression isn’t really an option. Instead, researchers have focused on looking for evidence of genetic influences on human sexual orientation through family and sibling studies, comparing heterosexuals with their homosexual relatives (usually siblings) through statistical analysis. Twin studies are the gold standard as the twins will almost always have been subject to the same environmental factors. What twin studies have revealed is that, while there is a definite genetic component: the likelihood of a twin being homosexual is hugely increased if the other is homosexual, though other factors are at play. These could still be purely biological and simply not on the genetic level.

Hormones studies in adults have found no significant difference between the circulating hormone level of a homosexual and a heterosexual. However, studies into prenatal levels of testosterone show high levels in males, low in females. They also look at other sex hormones, and their involvement in sexual differentiation of the body and brain may be where the answer lies. These studies follow from viewing orientation as part of a cluster of gender traits. The hypothesis is that a-typical levels of hormones can result in minute though significant changes in the sex-specific differentiation of the brain. How exactly the hormone levels change is unclear. Genetic and/or environmental factors could be responsible.

Neuroanatomical and cognitive studies have attempted to qualify these changes but, as with many complex biological problems, inconsistencies have arisen and replication is needed.

What’s most important is that science is no longer trying to find a cure to what was assumed an acquired disease but rather, trying to find a discrete grounding for what it has already found to be an innate phenomenon