Did scientists just discover some evidence that ‘gay genes’ exist?

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Scientists may have found genetic indicators of whether someone has same or opposite-sex attraction.

New research suggests that genetic code may play a role in determining sexual orientation.

The link was discovered when scientists compared the DNA of 47 sets of male twins.


The pairs included some where the two twins had a different sexual orientation.

Looking at the molecular data from nine genome sites, researchers could guess whether a twin pair was straight or gay with up to 70% accuracy.

Lead researcher Dr Tuck Ngun, from the University of California at Los Angeles, said: “To our knowledge, this is the first example of a predictive model for sexual orientation based on molecular markers.”

However some experts were sceptical of the study, which was presented at the annual meeting of the American Society of Human Genetics.

They said more work needed to be done in order to confirm the findings.

Researchers however, said the study provides evidence that environmental influences can affect sexual orientation by altering the activity of genes.

The effects, known as “eptigenetic”, involve the molecular modification of DNA, called methylation.

The team, led by Dr Ngun, created powerful computer software to look at patterns of the markers hidden within individuals’ DNA correlating with sexual orientation.

Nine small regions across the genome provided a close match between levels of the altered DNA behaviour, and whether the subject had same or opposite-sex attraction.

“Sexual attraction is such a fundamental part of life, but it’s not something we know a lot about at the genetic and molecular level,” said Dr Ngun. “I hope that this research helps us understand ourselves better and why we are the way we are.”

Out of the 47 pairs of twins, 37 were pairs where one identified as straight and one as gay, and 10 pairs were both gay.

Professor Tim Spector, from King’s College London, an expert on twin studies and genetics, commented on the study, saying: “It has always been a mystery why identical twins who share all their genes can vary in homosexuality.

“Epigenetic differences are one obvious reason and this study provides evidence for this. However the small study needs replicating before any talk of prediction is realistic.”