We have all heard a number of different versions of the origins of homosexuality. Psychologists were the first to offer their theories and probably the most well known is Freud’s theory of the ‘absent father’; it attributes a child’s same-sex attraction to emotional distance from his male parent (as with many other theories, no attempt is made to explain female homosexuality). Other theories speculate that the first sexual experience or seduction by an older person might condition the child’s future sexual preferences. Though Freud himself did not perceive homosexuality as a pathological condition, many other psychologists did so, grounding their views on these theories. Theses views found their place in medical practice, common views and prejudices, as well as in the practice of pastoral care provided by Churches. The Catechism of The Catholic Church, however, cautiously states that “psychological genesis [of homosexuality] remains largely unexplained”.

In the last few decades, a great deal of research into the biological causes of same-sex attraction has produced new perspectives on the origins of sexual orientation. Now and then, a search for what is commonly spoken about as a ‘gay gene’ provokes sensational headlines in the media, only to leave the public with even more questions than answers. This book, by two British researchers, is a long needed overview of the recent developments in psychology, neuroscience, endocrinology, genetics and evolutionary biology (the authors termed all these overlapping disciplines ‘psychobiology’) related to the origins of homosexuality.

Wilson and Rahman challenge the view that we all are ‘bisexual’, leaning to one or another direction. Kinsey’s famous report, supplemented with data from analogous studies from several countries, indicates the categorical (we are either straight or gay) and stable (comparatively unchanging during a lifetime) character of human sexuality. Real bisexuals are very few, however this is more true about men than women – “women have greater erotic plasticity … male and female sexual orientation may have divergent, though overlapping, causes” (p.27).

The authors insist, with the support of data from a number of surveys, that the number of homosexual people is smaller, no more than 3,5% among men and 1,5% among women, than it has been commonly assumed.

One of the strongest arguments for a genetic factor in sexual orientation is a well-documented observation that children who become lesbian or gay adhere less strongly to gender norms (“typical” for boys or girls behaviour) than those children who become heterosexual. This childhood gender nonconformity (CGN) has a strong heritable component and is not “treatable”. Though on the bases of CGN alone it is impossible to guess exactly the future sexual orientation of the child, a correlation between CGN and homosexuality suggests that the latest is also partly determined by genes.

Alhough the genetic factor in sexual orientation has its place (we also know this from research on identical twins), the authors admit a romanticised ‘gay gene’ as such does not exist; the environment has its role in the development of a sexual orientation, too. The authors attempt to situate a variety of available, rather fragmented, data into the context of evolutionary theory (i.e. if same-sex attraction has survived until now it must serve reproductive function in one or another way). If asked where homosexuals come from, Wilson and Rahman would confidently reply: exactly from where heterosexuals do. They endeavour to show how the same biological processes determine one or another sexual orientation; and those leading to same-sex attraction are no more pathological than those leading to heterosexual attraction.

The authors review, evaluate and compare dozens of studies which do not always support each other. They admit multiple difficulties still persist for understanding the origins of sexual orientation; the major obstacle for a deeper understanding being the lack of reliable, representative research into the issue. They are also careful not to undermine the apparent differences between male and female sexual development.

Despite dealing with the materials and minutiae of scientific research, the authors have managed to produce an illuminating, exciting and generally accessible book. It will certainly contribute to a better awareness of the complexity of the issue of same-sex attraction and, perhaps, to healing the vision of homosexuality as something either pathological or deserving celebration and pride.