Sex and Sexuality

Some notes on the scientific evidence for different views.

The Maleness Gene. The following account of current genetic knowledge is based on The Science Book edited by Peter Tallack (Cassell & Co 2001), page 502.

The chromosomal differences between men and women have been known for a long time. Usually, women have two X chromosomes and men have one X and one Y. But both male and female characteristics are sometimes found in one individual, and there are also XY women and XX men. Study of such individuals has revealed genes involved in sex determination. In cases of indeterminate or 'wrong' sex, one or more of these must be missing or defective. The most important of these genes is the SRY (sex-determining region Y) gene, which controls the formation of the testes. David Page developed the first gene map of the Y chromosome. Then, in the early 1990s Robin Lovell-Badge and Peter Goodfellow located SRY on this map in both men and mice. The protein encoded by SRY binds to DNA in the cell and alters its properties, with dramatic consequences for the embryo. The genital region develops into a penis and testes at around the twelfth week of gestation, while male hormones begin to act on the brain, and the body is shaped into a masculine rather than a feminine form. SRY [in humans] appears to have changed little in 200,000 years of human evolution. In other words we are all created as females at the moment of fertilisation. It is whether or not we possess an SRY gene that sets us on the path to being male or female at birth. Lovell-Badge and his co-workers proved this in 1991 when they inserted an SRY gene into female mouse embryos. The animals changed sex, developing testes and other male characteristics.

Procreation or Recreation? The main reason for the 'down' that religious authorities have on all expressions of sexuality other than copulation within marriage, is that they see it as serving the sole purpose of procreation and perpetuation of the species. All other expressions of sexuality are regarded as 'sins'. Why do they see it this way? Is it purely because of rules laid down by ancient patriarchal despots in the holy books? Or does it come from their fear of losing their own sexual self-control, that is from the repression of their sexuality? Obviously procreation is one of the main purposes of sex from the evolutionary point of view, but it also serves the major purpose of providing a bond of love and pleasure between individuals, which helps them to live together in harmony and cooperation, helping them to survive and prosper and find purpose and happiness in their lives.

Also from The Science Book (pages 444-5) is this extract by Jared Diamond, apparently from his book Why is Sex Fun?: Along with posture and brain size, sexuality completes the trinity of the decisive respects in which the ancestors of humans and great apes diverged. Orangutans are often solitary, males and females associate just to copulate, and males provide no paternal care; a gorilla male gathers a harem of a few females, with each of which he has sex at intervals of several years (after the female weans her most recent offspring and resumes menstrual cycling and before she becomes pregnant again); chimpanzees and bonobos live in troops with no lasting male-female pair-bonds or specific father-offspring bonds.

Sexual Orientation - Genetic or Cultural? I give here extracts from letters to Leicester Mercury that express different views on this subject. Barkat Rajani 19 December 2003: "It is indeed a very worrying trend that churches now not only allow gay bishops, but also allow same-sex unions ... None of the known religions - Judaism, Hinduism and Islam - condones homosexuality and lesbianism. In fact Christianity and the Bible, like the Islamic holy book, has extended stories of God (Allah), condemning ... these immoral practices. I trust leaders of all religions, especially the Christians, shall take this issue seriously and come out openly in not accepting these in their midst." Colin Mattock 26 December 2003: "How small-minded Barkat Rajani revealed himself to be with his outmoded and offensive views on homosexuality. [He] seems to believe that homosexuality is an immoral and selfish indulgence and a deliberate affront to God rather than the genetically programmed predisposition all educated people know it to be." George Jelliss 1 January 2004: I don't know why Barkat Rajani considers gay bishops and same-sex unions immoral, since the teachings attributed to Jesus and, before him, Krishna and Buddha, place emphasis on loving relationships. ... I don't know whether homosexuality is a 'genetically programmed predisposition' ... But after looking at all the scientific evidence I could trace, it seems to suggest that genetic causation if any is slight, and that hormonal, developmental and cultural influences are stronger. My theory, for what it's worth, is that everyone is born without any sexual bias, and that the majority become 'hetero', through fear of being thought other, because of the overwhelmingly macho culture of our patriarchal society." John Kirk 10 January 2004: In some respects Christianity is very tolerant. For example it offers a guaranteed plan of salvation to all regardless of race, creed or colour, no matter how heinous one's past life and actions, which religious practices have been followed or how perverse one's personal relations. In other respects Jesus' teachings are very intolerant. He is quite clear about any relationships outside marriage: "For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies. These are the things which defile a man." Nowhere in the Bible is there any hint of approval at any sexual relations outside marriage, regardless of gender.

I e-mailed Brett Humphreys of GALHA for views on the validity or otherwise of homosexuality being a 'genetically programmed predisposition' and received the following reply: Brett Humphreys 4 January 2004: "This is a view often expressed by gay people - largely, I think, in the hope of invalidating the efforts of the fundamentalist Christian groups known as the 'ex-gay' movement (who are particularly active in the US) to 'convert' people to heterosexuality, in which case it reflects confusion of a scientific issue with an ethical one. Whether the genetic theory has a scientific basis remains controversial. It's a theme I contemplated using for one of my 'Web Watch' columns in 'Gay and Lesbian Humanist' but I never got round to finding the time to do the necessary research, and I've just given up doing the column. You should find the 'Knitting Circle' section on genetics a good starting point. It includes pages on three individuals whose names are particularly associated with the so-called 'Gay Gene' theory - Dean Hamer (who started it in 1993), Simon LeVay and Chandler Burr. Hamer and LeVay are scientists; Burr is a journalist. LeVay and Burr have their own websites, which you'll find listed on the respective Knitting Circle pages. Sorry I can't be of more help. But if you do decide to explore this topic in greater depth, I'd be interested to hear what conclusions you reach."

More from GALHA: There's an interesting 4-page article in New Scientist (17 January 2004, pp. 36-39) challenging Charles Darwin's theory of sexual selection (NB: not natural selection). — NS blurb: Same-sex relationships are not a biological dead end. They are a glue that helps hold many animal societies together, and a fatal flaw in one of Darwin's central ideas, argues evolutionary ecologist Joan Roughgarden. — The article isn't (and won't be) available online except by subscription, but if you can get hold of the print edition it's worth a read. Failing that, here's a synopsis from the Guardian (14 August 2003):,12982,1017904,00.html The New Scientist article is really a trailer for Roughgarden's forthcoming book Evolution's Rainbow: Diversity, Gender and Sexuality in Nature and People, which is due out in May [2004]: For interest, here's some further background: and here's an acrimonious row between Joan Roughgarden and Simon LeVay: and

Links to Relevant Sites

Biology and Genetics
Knitting Circle - genetics
Homosexuality - a Christian Perspective
Dean Hamer et al - abstract of paper on 'gay gene'
Born Gay - a skeptical view
Religious Tolerance Org. - Homosexuality: chosen lifestyle or fixed orientation?
Twin Studies of Homosexuality - a survey
Was Darwin Wrong? - Reviews by G. Korthof
American Library Association - Booklist
The above two sites include reviews of the book Biological Exuberance: Animal Homosexuality and Natural Diversity by Bruce Bagemihl.
GALHA, genetics page - Three articles relating to the 'gay gene' controversy.

Bisexual, Gay and Lesbian Groups
Leicester Lesbian and Gay Action
Gay/Lesbian Search Engine
Gay and Lesbian Humanist Association (UK)
Gay and Lesbian Atheists and Humanists (USA)

This essay is based on a page that first appeared on the Leicester Secular Society website in 2004.