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. 

Even Science Daily, in reporting in 2012 on the latest research proposal (on epigenetics), stated, "However, no major gene for homosexuality has been found despite numerous studies searching for a genetic connection."

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. In fact, we know many people who have once experienced same-sex attraction but are now married with children.

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 'twins' study, by Richard Pillard and Michael Bailey, done in the USA, asked homosexuals who had twins to take part in a study. Many of the participants were recruited through homosexual newspapers. The original study found that if a homosexual was an identical twin then there was about 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 since they share the same genes!

Bailey did a more authoritative study on Australian twins in 2000, using the Australian Twin Register to get people for the study. He acknowledged the 'selection bias' in his previous sample. The result was much lower. Neil Whitehead notes, "Jones and Yarhouse, for the important Australian Bailey et al. (2000) SSA twin study paper, find that for self-declared lesbians and homosexual men the pairwise concordance is 14% and 11% respectively." See My Genes Ch 10.

Neil also describes the difference between probandwise concordance (which is often used in the official studies - where each 'match' is counted twice, one for EACH of the homosexual brothers! This gives a 'higher figure') and pairwise concordance, which asks the question, "If one twin of an identical pair is SSA, what percentage of co-twins are also SSA?"

Jones and Yarhouse note that Bailey et al actually wrote that the study "did not provide statistically significant support for the importance of genetic factors” for homosexual orientation." Jones and Yarhouse wrote a book - but a good overview of the book is here.

Even in the Australian study people on the Twins Register 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.

Neil Whitehead has analysed the results of such studies. He writes, "From six studies (2000-2011): if an identical twin has same-sex attraction the chances that the co-twin has it too are only about 11% for men and 14% for women. This means that factors the twins have in common, such as genes and upbringing are mostly not responsible – individual and idiosyncratic responses to random events and to common factors predominate." Source.

A 2013 article by Bryan Fischer of the American Family Association, refers to Jason Collins, a US basketballer 'coming out' as a homosexual. First, it is noted that he had a female fiancee for eight years! 

Bryan notes he is an identical twin and writes, "One other significant, significant piece of this story is that Jason Collins is absolute proof that homosexuals aren’t “born that way,” despite the bloviations of that noted geneticist Lady Gaga.

Jason Collins has an identical twin, Jarron, who was “astounded” to discover that his brother had entered into the homosexual lifestyle. He, despite sharing Jason’s identical DNA, is as straight as a laser beam. Identical twins share traits that are genetically determined: height, skin color, eye color, hair color and so forth. If homosexuality is a genetically-caused sexual preference, Jarron Collins should be as gay as his brother. He’s not.

Peter Bearrman, a researcher from Columbia, and Hannah Bruckner, a researcher from Yale (note: neither part of the vast right-wing conspiracy) carefully examined data from the National Longitudinal Study of Adolescent Health to determine the “concordance” rate of identical twins on matters of sexual identity.

The concordance rate ought to be 100%. It isn’t. In fact, Bearrman and Bruckner discovered that the concordance rate was in fact astonishingly low: just 6.7% for male identical twins and 5.3% for female identical twins.

Their conclusion: “[O]ur results support the hypothesis that less gendered socialization in early childhood and preadolescence shapes subsequent same-sex romantic preferences.” In other words, life experience shapes sexual preferences, not DNA.

Almost immediately the pro-homosexual groups starting labelling the AFA and Bryan Fischer as a 'hate group' - see here - and the article was removed!
The Wall Street Journal article highlights the debate.

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, 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.
His response to the Wikpedia article is here.

A further study on the hypothalamus was published in 2001 by Byrne and others.

Research into other possible 'causes'

Other possible 'causes' for homosexuality have been investigated. Some research has been done about the possibility of the influence of hormones in the womb. Other studies have looked at the 'fraternal birth order effect (FBOE)' - part of that is a speculation that a mother's body produces antibodies whilst pregnant that leads to the child being homosexual.

Dr Warren Throckmorton writes about one study investigating this. He notes that there is no actual evidence for this theory, but that there were numerous headlines announcing the 'study' and the 'results'!

He then notes that the media ignored another study, in 2002, published in the American Journal of Sociology, by Peter Bearman (Columbia) and Hannah Brückner (Yale). They studied factors related to same-sex attraction. They assessed 20,745 young people, and attributed homosexuality to environment and sociological factors and found NO link to the fraternal birth order 'theory'.

They concluded, “Our results support the hypothesis that less gendered socialization in early childhood and preadolescence shapes subsequent same-sex romantic attraction.” They added, "If same-sex romantic attraction has a genetic component, it is massively overwhelmed by other factors."
Read Dr Throckmorton's article: The Study The Media Ignored