Yet another study has suggested that we could be closing in on so-called ‘gay genes’.
The genetic analysis of 409 pairs of gay brothers, which included twins, provides the most compelling evidence so far that people are born gay.
The study strengthens theories that two regions, one on the X chromosome and one on chromosome 8, could be linked to sexual orientation in men.
It is the largest study of its kind by about three times the numbers of the previous record.
The leader of the study, Alan Sanders, of the NorthShore Research Institute in Evanston, Illinois, says the study will counter the idea that sexual orientations can be “cured” or “treated”.
“It erodes the notion that sexual orientation is a choice,” says Sanders.
One of the regions, on the X chromosome, called Xq28, was first identified over two decades ago in 1993, by Dean Hamer of the US National Institutes of Health in Bethesda, Maryland.
Research since then has been mixed, however.
A second region, 8q12, was first noted in 2005.
To compare, this study looked at 409 pairs of gay brothers, and non-identical twins, from 384 families, but Hamer’s 1993 study only looked at 40 pairs of gay brothers.
Although Sanders’ work does close in on potentially locking down genes which are linked to sexual orientation, he say there is much work still to be done.
Scientists earlier this year believed to have found genetic indicators of whether someone has same or opposite-sex attraction.
The research released in October suggested 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.