.

  • Written by Brendan Zietsch, ARC Future Fellow, The University of Queensland
The biology of same-sex attraction seems to involve a host of genes. Dewald Kirsten/Shutterstock

It has long been clear that a person’s sexual preference – whether they prefer male or female sexual partners, or both – is influenced by his or her genetic makeup. The most straightforward evidence for this is that sexual preference is more likely to be the same in identical twin pairs, whose genetic makeup is identical, than in non-identical twin pairs, who share only around 50% of their genetic makeup.

What has been elusive is knowledge of what specific gene, or genes, are involved. A 1993 study found male sexual preference was influenced by a particular gene on the X chromosome, which the media naturally dubbed the “gay gene”. But a later study did not replicate this finding, and subsequent follow-ups yielded mixed results.


Read more: Born this way? An evolutionary view of 'gay genes'


The problem was that these studies were too small to draw confident conclusions. There are millions of parts of our DNA that commonly differ between people. That means finding the genes associated with sexual preference is like finding a needle in a haystack.

So an international team of researchers, which I led, set out to tackle this problem. Our results are published today in Science.

Forceful approach

Our approach was simple: brute force. All else being equal, the larger a study, the more confident we can be in the results. So instead of sampling a few hundred or a few thousand individuals – as in previous genetic studies on sexual preference – we used a sample of nearly half a million.

To obtain such a large sample, we used data that had been collected as part of much broader projects. These included DNA data and responses to questionnaires from participants in the UK (as part of the UK Biobank study) and the US (as part of data collected from customers of the commercial ancestry firm 23andMe who consented to answering research questions about sexuality).

The downside of using these huge data sets was that the studies were not specifically designed to find genes for sexual preference, so we were limited by the questions participants happened to have been asked about their sexual behaviour. For both UK Biobank and 23andMe, participants reported whether they had ever had a same-sex sexual partner.

A person’s DNA essentially consists of millions of letters of code, and the letters differ among different individuals. So, to make a complicated story short, the next step was to test at every DNA location whether one letter was more common in participants who reported any same-sex partners than in those who reported only opposite-sex partners.

Not one gene but many

What we found is that there is no one “gay gene” – instead, there are many, many genes that influence a person’s likelihood of having had same-sex partners.

Individually, each of these genes has only a very small effect, but their combined effect is substantial. We could be statistically confident about five specific DNA locations; we could also tell with high confidence that there are hundreds or thousands of other locations that also play a role, although we couldn’t pinpoint where they all are.

Participants in the 23andMe data set answered questions not only about their sexual behaviour, but also attraction and identity. Taking all the genetic effects in combination, we showed that the same genes underlie variation in same-sex sexual behaviour, attraction, and identity.

Some of the genes that we could be sure about gave us clues about the biological underpinnings of sexual preference. One of those genes, as well as being associated with same-sex sexual behaviour in men, was also associated with male pattern balding. It is also near a gene involved in sexual differentiation – the process of masculinisation and feminisation of biological males and females, respectively. Sex hormones are involved in both baldness and sexual differentiation, so our finding implies that sex hormones may be involved in sexual preference too.

Other findings further reinforced the extreme complexity of the biology underlying sexual preference. First, genetic influences only partly overlapped in males and females, suggesting the biology of same-sex behaviour is different in males and females.

Second, we established that, on the genetic level, there is no single continuum from gay to straight. What’s more likely is that there are genes that predispose to same-sex attraction and genes that predispose to opposite-sex attraction, and these vary independently.

Because of the complexity of the genetic influences, we cannot meaningfully predict a person’s sexual preference from their DNA – nor was this our aim.

Possible misinterpretations

Scientific findings are often complex, and it is easy for them to be misrepresented in the media. Sexual preference has a long history of controversy and public misunderstanding, so it is especially important to convey a nuanced and accurate picture of our results.

But people tend to want black-and-white answers about complex issues. Accordingly, people may react to our findings by saying either: “No gay gene? I guess it’s not genetic after all!” or “Many genes? I suppose sexual preference is genetically fixed!” Both of these interpretations are wrong.


Read more: Differences between men and women are more than the sum of their genes


Sexual preference is influenced by genes but not determined by them. Even genetically identical twins often have completely different sexual preferences. We have little idea, though, what the non-genetic influences are, and our results say nothing about this.

To answer further questions the public might have about the study, we created a website with answers to frequently asked questions, and an explanatory video. In developing this website we drew on feedback from LGBTQ outreach and advocacy groups, dozens of LGBTQ rights advocates and community members, and workshops arranged by Sense about Science where representatives of the public, activists, and researchers discussed the results of the study.

Brendan Zietsch receives funding from the Australian Research Council. He is senior author on the paper discussed.

Authors: Brendan Zietsch, ARC Future Fellow, The University of Queensland

Read more http://theconversation.com/gay-gene-search-reveals-not-one-but-many-and-no-way-to-predict-sexuality-122459

Reality slippages and narcissistic stereotyping - watching Content, a TV show made for smart phones

Lucy spends much of her life living through her phone screen – what happens when we are let into this vantage point? Mia Forrest/ABCLucy (Charlotte Nicado) is a pink-haired millennial having a q...

Emma Maguire, Lecturer in English and Creative Writing, James Cook University - avatar Emma Maguire, Lecturer in English and Creative Writing, James Cook University

You can help track 4 billion bogong moths with your smartphone – and save pygmy possums from extinction

Healesville Sanctuary, Werribee Open Range ZooEach year, from September to mid-October, the tiny and very precious mountain pygmy-possums arise from their months of hibernation under the snow and beg...

Sally Sherwen, Director Wildlife Conservation and Science, Zoos Victoria, University of Melbourne - avatar Sally Sherwen, Director Wildlife Conservation and Science, Zoos Victoria, University of Melbourne

Is vigorous exercise safe during the third trimester of pregnancy?

Vigorous exercise is safe while pregnant, even in the final trimester. But if you don't feel up to it, lighter exercise is beneficial too. From shutterstock.comExpectant mothers receive an avalanche o...

Kassia Beetham, Exercise Physiology Lecturer, Australian Catholic University - avatar Kassia Beetham, Exercise Physiology Lecturer, Australian Catholic University

Climate change is the defining issue of our time – we're giving it the attention it deserves

The Conversation has joined more than 250 news outlets around the world to focus on climate change coverage. We provide 100% evidence-based coverage on climate change. Stay informed BY subscribing to...

Nicole Hasham, Section Editor: Energy + Environment - avatar Nicole Hasham, Section Editor: Energy + Environment

Australia to attend climate summit empty-handed despite UN pleas to ‘come with a plan'

The Port Kembla industrial area in NSW. Industry emissions can be cut by improving efficiency, shifting to electricity and closing old plants. Dean Lewins/AAPThis story is part of Covering Climate Now...

Frank Jotzo, Director, Centre for Climate and Energy Policy, Crawford School of Public Policy, Australian National University - avatar Frank Jotzo, Director, Centre for Climate and Energy Policy, Crawford School of Public Policy, Australian National University

'Climigration': when communities must move because of climate change

Flood damage in Bundaberg, Queensland, in 2013. Most communities are at some risk from extreme events, but repeated disasters raise the question of relocation. srv007/Flickr, CC BY-NCThis story is par...

Tony Matthews, Senior Lecturer in Urban and Environmental Planning, Griffith University - avatar Tony Matthews, Senior Lecturer in Urban and Environmental Planning, Griffith University

As Scott Morrison heads to Washington, the US-Australia alliance is unlikely to change

Wes Mountain/The Conversation, CC BY-NDPrime Minister Scott Morrison’s official visit to Washington this week carries some prestige. It is just the second “official visit” (includin...

David Smith, Senior Lecturer in American Politics and Foreign Policy, Academic Director of the US Studies Centre, University of Sydney - avatar David Smith, Senior Lecturer in American Politics and Foreign Policy, Academic Director of the US Studies Centre, University of Sydney

Apple's iPhone 11 Pro wants to take your laptop's job (and price tag)

What a week it has been in the Apple core. In recent days the tech giant has released a litany of products, including new phones, watches, tablets, and more. The big-ticket items are clearly the new ...

Andrew Maxwell, Senior Lecturer, University of Southern Queensland - avatar Andrew Maxwell, Senior Lecturer, University of Southern Queensland

A loaf of bread and a packet of pills: how supermarket pharmacies could change the way we shop

Supermarket pharmacies have been around in the US, UK and mainland Europe for years. But will Australia follow? from www.shutterstock.comOn the way home, you wander into the supermarket for a loaf of ...

Gary Mortimer, Professor of Marketing and Consumer Behaviour, Queensland University of Technology - avatar Gary Mortimer, Professor of Marketing and Consumer Behaviour, Queensland University of Technology

Bushwalking and bowls in schools: we need to teach kids activities they'll go on to enjoy

Schools could use bushwalking as an activity and link it to lessons in other subjects such as geography and science. Shutterstock/Monkey Business ImagesPhysical education is one of the most popular su...

Vaughan Cruickshank, Program Director – Health and Physical Education, Maths/Science, Faculty of Education, University of Tasmania - avatar Vaughan Cruickshank, Program Director – Health and Physical Education, Maths/Science, Faculty of Education, University of Tasmania

Picking The Right Crystal Yoni Egg: Tips And Instructions

When you are ready to pick your own crystal yoni egg, you need to decide what you will use it for, how big it should be, and how many you need. Some people who would like to use the egg because they...

News Company - avatar News Company

View from The Hill: Morrison's right hand man dispenses with niceties in lecturing big business

The Morrison government appears to be seething with anger at big business. At least, that’s the impression you get from a lecturing, hectoring speech delivered this week by Ben Morton, who&rsquo...

Michelle Grattan, Professorial Fellow, University of Canberra - avatar Michelle Grattan, Professorial Fellow, University of Canberra

New musical has enough warmth, witty lines and catchy tunes to win its own fangirls

Sharon Millerchip, Ayesha Madon, James Majoos, Chika Ikogwe, and Kimberley Hodgson in Fangirls at the Brisbane Festival. Photo: Stephen HenryComedy often succeeds where tragedy fails. Fangirls, the...

Alastair Blanshard, Paul Eliadis Chair of Classics and Ancient History Deputy Head of School, The University of Queensland - avatar Alastair Blanshard, Paul Eliadis Chair of Classics and Ancient History Deputy Head of School, The University of Queensland

Polycystic kidney disease, the most common genetic kidney disorder you've probably never heard of

If one parent has ADPKD, their child has a one in two chance of getting it. From shutterstock.comAutosomal-dominant polycystic kidney disease (ADPKD) is the most common genetic kidney disorder, and th...

Karen Dwyer, Deputy Head, School of Medicine, Deakin University - avatar Karen Dwyer, Deputy Head, School of Medicine, Deakin University

VIDEO: Michelle Grattan on Gladys Liu and the government's plan to drug-test welfare recipients

Liberal MP Gladys Liu has beeb the centre of much heated debate in federal politics this week. AAP/Lukas CochMichelle Grattan speaks with University of Canberra Vice-Chancellor and President Professo...

Michelle Grattan, Professorial Fellow, University of Canberra - avatar Michelle Grattan, Professorial Fellow, University of Canberra

Bupa's nursing home scandal is more evidence of a deep crisis in regulation

Australia's Aged Care Quality and Safety Commission found 45 of Bupa's 72 nursing homes failed health and safety standards. In 22 homes the health and safety of residents was deemed at 'serious risk...

Benedict Sheehy, Associate professor, University of Canberra - avatar Benedict Sheehy, Associate professor, University of Canberra

Actually, it's OK to disagree. Here are 5 ways we can argue better

When we fail to consider the ethics of arguing, this makes it perilously easy to mistreat others. ShutterstockArgument is everywhere. From the kitchen table to the boardroom to the highest echelons of...

Hugh Breakey, Senior Research Fellow, Moral philosophy, Institute for Ethics, Governance & Law, Law Futures Centre, Griffith University - avatar Hugh Breakey, Senior Research Fellow, Moral philosophy, Institute for Ethics, Governance & Law, Law Futures Centre, Griffith University

Women may find it tougher to get an abortion if the religious discrimination bill becomes law

Women may need to shop around for a new doctor if the first one refuses to perform an abortion for religious reasons. from www.shutterstock.comIf the Religious Discrimination Bill passes into law, wom...

Elizabeth Shi, Lecturer, Graduate School of Business and Law, RMIT University - avatar Elizabeth Shi, Lecturer, Graduate School of Business and Law, RMIT University

Why declaring a national climate emergency would neither be realistic or effective

The Greens and independent MPs are pushing for Australia to declare a national 'climate emergency', in line with several other nations. Darren England/AAPPredictably, both major political parties are ...

David Holmes, Director, Climate Change Communication Research Hub, Monash University - avatar David Holmes, Director, Climate Change Communication Research Hub, Monash University

Sick and Tired of Your Dead End Job? Try Teaching!

Tired of the same old grind at the office? Want an opportunity to impact lives both in your community and around the world? Do you love to travel and have new experiences? Teaching English is the perfect job for you! All you need is a willingness to ...

News Company - avatar News Company

The Impact of an Aging Population in Australia

There’s an issue on the horizon that Australia needs to prepare for. The portion of elderly citizens that make up the country’s overall population is increasing, and we might not have the infrastructure in place to support this. Australians h...

News Company - avatar News Company

LifeStyle

Picking The Right Crystal Yoni Egg: Tips And Instructions

When you are ready to pick your own crystal yoni egg, you need to decide what you will use it for...

Top 5 Tips for Paddleboarding In Whitewater

Paddleboarding can be relaxing as well as intense. If you occasionally want to do something differen...

3 Most Promising Career Occupations for Graduates in 2019

Studying in college is a great adventure which opens up lots of career opportunities. Yet, at times...

SCARmed Silicone Gel

AUSTRALIA LEADS WAY WITH ALL-NEW RAPID-DRYING SILICONE GEL WORKING WONDERS IN SCAR REDUCTION   ...