Male homosexuality influenced by genes, US study finds

Gay men share genetic traits, but other factors play a role in their sexual orientation, say American scientists

An American study has found new evidence that male homosexuality is influenced by genes – but environmental and social factors also play a role.

In the study, which was presented at a Science of Sex and Attraction event in Chicago, scientists tested the DNA of more 400 sets of gay brothers and their heterosexual relatives, to find out if some men are predisposed to being gay.

Genetic factors account for between 30 per cent and 40 per cent of what decides whether a man is gay or straight, according to the research.

Scientists found that a region of the X chromosome Xq28 had an impact on male sexuality, as did a stretch of DNA on chromosome 8.

Dr Michael Bailey, of Northwestern University, Illinois, who col-led the study said: “Sexual orientation has nothing to do with choice. Our findings suggest there may be genes at play – we found evidence for two sets that affect whether a man is gay or straight.

“But it is not completely determinative; there are certainly other environmental factors involved.”

The work has not yet been published, but it builds on a previous study carried out in 1993 by Dr Dean Hamer from the US National Cancer Institute, who also found that gay men shared genetic signatures on the X chromosome.

However, the findings of the study raise the prospect of a genetic test that could be used to determine a bay’s sexual orientation in the womb.

“Although this could one day lead to a pre-natal test for male sexual orientation, it would not be very accurate, as there are other factors that can influence the outcome,” Dr Bailey said.

“Clearly parents should not be allowed to torture or kill babies. But they can currently choose to terminate a pregnancy early on, so they should be allowed to have as much information on the future child as possible.”

But Dr Alan Sanders, clinical associate Professor of Psychiatry at Northwestern University, who led the study, said that identifying a specifically “gay gene” was “oversimplification” .

“We also don’t think genetics is the whole story. It’s not.  And whatever genes contribute to sexual orientation, you can think of it contributing to heterosexuality as much as you can think of it contributing to homosexuality. It contributes to variation of a trait,” he said.

Last year, Canadian scientists found that the more older male siblings a man has, the more likely he is to be gay.

They said this is because carrying a boy in the womb triggers an immune response in the mother, which has an impact on the unborn baby’s sexual orientation.

The more boys a woman carries, the stronger the response.

Dr Bailey said environmental factors were likely to have the biggest impact on homosexuality.

“Don’t confuse “environmental” with “socially acquired.” Environment means anything that is not in our DNA at birth, and that includes a lot of stuff that is not social,” he said.

Richard Lane, a spokesman for Stonewall, said: "These kinds of studies come along every so often; they purport to prove the origins of sexual orientation without really backing the research up.

"If someone is gay, then they deserve respect and equality regardless."

Start your day with The Independent, sign up for daily news emails
PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
ebooks
ebooksA special investigation by Andy McSmith
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Online Media Sales Trainee

£15000 - £30000 per annum: Recruitment Genius: Now our rapidly expanding and A...

Recruitment Genius: Public House Manager / Management Couples

£15000 - £20000 per annum: Recruitment Genius: Are you passionate about great ...

Recruitment Genius: Production Planner

£20000 - £30000 per annum: Recruitment Genius: This fast growing reinforcing s...

Recruitment Genius: General Factory Operatives

£18000 - £35000 per annum: Recruitment Genius: This fast growing reinforcing s...

Day In a Page

As in 1942, Germany must show restraint over Greece

As in 1942, Germany must show restraint over Greece

Mussolini tried to warn his ally of the danger of bringing the country to its knees. So should we, says Patrick Cockburn
Britain's widening poverty gap should be causing outrage at the start of the election campaign

The short stroll that should be our walk of shame

Courting the global elite has failed to benefit Britain, as the vast disparity in wealth on display in the capital shows
Homeless Veterans appeal: The rise of the working poor: when having a job cannot prevent poverty

Homeless Veterans appeal

The rise of the working poor: when having a job cannot prevent poverty
Prince Charles the saviour of the nation? A new book highlights concerns about how political he will be when he eventually becomes king

Prince Charles the saviour of the nation?

A new book highlights concerns about how political he will be when he eventually becomes king
How books can defeat Isis: Patrick Cockburn was able to update his agenda-setting 'The Rise of Islamic State' while under attack in Baghdad

How books can defeat Isis

Patrick Cockburn was able to update his agenda-setting 'The Rise of Islamic State' while under attack in Baghdad
Judith Hackitt: The myths of elf 'n' safety

Judith Hackitt: The myths of elf 'n' safety

She may be in charge of minimising our risks of injury, but the chair of the Health and Safety Executive still wants children to be able to hurt themselves
The open loathing between Barack Obama and Benjamin Netanyahu just got worse

The open loathing between Obama and Netanyahu just got worse

The Israeli PM's relationship with the Obama has always been chilly, but going over the President's head on Iran will do him no favours, says Rupert Cornwell
French chefs get 'le huff' as nation slips down global cuisine rankings

French chefs get 'le huff' as nation slips down global cuisine rankings

Fury at British best restaurants survey sees French magazine produce a rival list
Star choreographer Matthew Bourne gives young carers a chance to perform at Sadler's Wells

Young carers to make dance debut

What happened when superstar choreographer Matthew Bourne encouraged 27 teenage carers to think about themselves for once?
Design Council's 70th anniversary: Four of the most intriguing prototypes from Ones to Watch

Design Council's 70th anniversary

Four of the most intriguing prototypes from Ones to Watch
Dame Harriet Walter: The actress on learning what it is to age, plastic surgery, and her unease at being honoured by the establishment

Dame Harriet Walter interview

The actress on learning what it is to age, plastic surgery, and her unease at being honoured by the establishment
Art should not be a slave to the ideas driving it

Art should not be a slave to the ideas driving it

Critics of Tom Stoppard's new play seem to agree that cerebral can never trump character, says DJ Taylor
Bill Granger recipes: Our chef's winter salads will make you feel energised through February

Bill Granger's winter salads

Salads aren't just a bit on the side, says our chef - their crunch, colour and natural goodness are perfect for a midwinter pick-me-up
England vs Wales: Cool head George Ford ready to put out dragon fire

George Ford: Cool head ready to put out dragon fire

No 10’s calmness under pressure will be key for England in Cardiff
Michael Calvin: Time for Old Firm to put aside bigotry and forge new links

Michael Calvin's Last Word

Time for Old Firm to put aside bigotry and forge new links