Homosexuality - is it genetic?

Over the years there has been considerable debate about whether homosexuality is genetic - biologically determined by our DNA and genes - or whether it is the result of environmental and other factors. This is often described as the 'nature v nurture' debate.

Over the years numerous research projects have been conducted. However there is no conclusive evidence that homosexuality is genetic. 

The issue is of particular importance, since there are some who claim that if one is 'born that way' then you cannot change...
At Salt Shakers, we maintain that homosexuality is not genetic and that change of one's sexual orientation is possible.

Neil Whitehead
Neil Whitehead is a NZ scientist/researcher who has analysed and collated the evidence over many years and has written a book on the topic: My genes made me do it.
The book, which is regularly updated, contains an excellent summary of the evidence. His research shows that homosexuality is not 'genetic'.

The book can be downloaded on his website. Click here for the 'My Genes' website.

NARTH - National Association for Research & Therapy of Homosexuality
NARTH has extensively analysed the claims relating to whether homosexuality is genetic. Their position statement page addresses this matter - along with others.
List of articles on NARTH website addressing the 'born that way' or 'genetic' theory.

Reprints/synopses of NARTH conference articles/reports and synopses of articles/resources.

The Biological Research on Homosexuality 
Book Excerpt: Homosexuality and American Public Life (Edited by Christopher Wolfe)
The article is from Dr. Jeffrey Satinover's chapter, entitled, "The Biology of Homosexuality: Science or Politics?" which provides a very comprehensive review of the biological research on homosexuality.

The Myth Of The Gay Gene- By Father Nicanor Pier Giorgio Austriaco, Ph.D. First published in Homiletic & Pastoral Review, December 2003.

 

Studies on 'genes'

There have been three main studies conducted regarding homosexuality and genetics. Often those conducting the research are homosexuals themselves and are sometimes activists.

The results from the studies have never been replicated - and sometimes even the researchers themselves have commented that the popular media have 'magnified' and expanded the results.

1. Dean Hamer - X chromosome
The science of desire: The search for the gay gene and the biology of behavior - Hamer, D., & Copeland, P. (1994).  New York: Simon & Schuster.

Dean Hamer investigated the X chromosome - but the results were inconclusive. They have not been replicated.
Others have shown that the X-chromosome-linked gene, if it applies at all, could only account for a 'modest amount of variance in sexual orientation' (Hu et al, 1995)
Hamer was later investigated for 'selecting the 'data' for his study.

2. Pillard and Bailey - Twin studies
The original study by Pillard and Bailey asked homosexuals who had twins to take part in a study. They were recruited through homosexual newspapers. The original study found that if they were identical twins then there was a 50 % chance of the identical twin also being homosexual - the percentage was 20% for fraternal twins.

Of course, if it really was 'genetic' it should be 100% for identical twins!

Bailey did a more authoritative study on Australian twins in 2000, using the Australian Twin Register to get people for the study. This time his result was 25% for identical twins and 10 % for fraternal twins.
He acknowledges the 'self-selecting problems' from his original study.
Even in the Australian study people were asked if they would answer questions on sex - if they agreed they were sent a questionnaire. 28% refused to participate and 54% completed a questionnaire.

The Australian study: Genetic and Environmental Influences on Sexual Orientation and Its Correlates in an Australian Twin Sample [Personality Processes and Individual Differences]
Bailey, Michael; Dunne, Michael; Martin, Nicholas. Journal of Personality and Social Psychology - American Psychological Association, Inc. Volume 78(3) March 2000 p 524-536

Discussion of the study in the following article:
The DNA Files - Unraveling the Mysteries of Genetics - DNA and Behavior: Is Our Fate In Our Genes? 
This discussion on DNA and genes mentions some of the flaws in Bailey's studies.

3. Simon Le Vay - hypothalamus
In his research Simon Le Vay analysed the hypothalamus of dead people - male, female, homosexual and heterosexual.

In 1991, Le Vay published "A difference in hypothalamic structure between heterosexual and homosexual men" in Science. The study reported that the hypothalamus of homosexual and heterosexual men were different. However the data was not conclusive.
Regardless, the media often reported he had found a genetic cause of homosexuality.
In 1994, in an article in Discover Magazine, Le Vay cautioned about misinterpreting his work. He wrote "It's important to stress what I didn't find. I did not prove that homosexuality is genetic or find a genetic cause for being gay. I didn't show that gay men are born that way, the most common mistake people make in interpreting my work. Nor did I locate a gay center in the brain."
Simon Le Vay's research and reports are discussed in this Wikipedia article.