Scientists in the US looked at the whole genomes of around 1000 homosexual men and 1200 heterosexual men, finding several stretches of DNA where there were more differences between the groups than would be expected by chance. But the researchers caution their results are “best described as speculative”.
The authors of the study, published in Scientific Reports, were looking for differences in single letters of DNA between the groups of homosexual and heterosexual men. The two regions of the genome with the most differences were near genes whose roles might be linked to sexual orientation.
One gene is linked to the development of a brain region which can differ in men depending on their sexual orientation while the other gene is linked to thyroid function, which has previously been linked to male homosexuality, according to the authors.
“It is well established from twin and family studies that sexual orientation is partly heritable – that is, that whether someone is straight or bisexual or gay depends partly on their genetic makeup,” [said] Dr Brendan Zietsch.
“Because there are so many bits of DNA (millions) that vary among people, finding the relevant bits is like finding a needle in a haystack,” continued Zietsch.
According to [Dr. Nina] McCarthy, with any genome-wide association study “it’s really important to appreciate that association does not imply causation”.
Read full, original post: ‘Speculative’ genetic link to homosexuality found