A new scientific study of 409 pairs of gay brothers could put to rest decades of debate over the existence of the so-called ‘gay gene’.

Research conducted by the NorthShore Research Institute in the US found clear links between male sexual orientation and two specific regions of the human genome, with lead scientist Alan Sanders declaring that the work “erodes the notion that sexual orientation is a choice”.

The study is three times larger than any previously done and highlights two genetic regions that have been tied to male homosexuality in separate research: Xq28, first identified in 1993, and 8q12, spotted in 2005.

However, Sanders does not claim to have identified a single gene which ‘causes’ male homosexuality in humans and stresses that with complex human traits like sexual orientation there are many influencing factors, both genetic and environmental.

For the study Sanders and his team collected blood and saliva from 409 pairs of gay brothers and analysed their genetic code for markers known as single nucleotide polymorphisms (SNPs).

Although Xq28 and 8q12 were the two regions that were most frequently identified as home to genetic markers common among the 818 gay men, three other SNPs were also highlighted.

Speaking to the New Scientist, neuroscientist Simon LeVay commented: “This study knocks another nail into the coffin of the 'chosen lifestyle' theory of homosexuality.”

"Yes, we have a choice in life, to be ourselves or to conform to someone else's idea of normality, but being straight, bisexual or gay, or none of these, is a central part of who we are, thanks in part to the DNA we were born with,” said LeVay, who previously claimed to have found a region of the brain that was smaller in gay men.

However, the announcement is unlikely to be met with great acclaim in the LGBT community, with Samantha Allen at The Daily Beast pointing to the murky history of conclusive evidence for any genetic causation.

She writes: “If it’s hard to get excited about these studies, it’s because, at this point, biological explanations for homosexuality are like iPhones—a new one comes out every year.”