It has long been debated whether sexual orientation really is a result of a person’s biology or whether it is determined by environmental factors and outside influences. A new study in the US could now bring experts a step closer to discovering where exactly an individuals sexuality is rooted from. While it’s no secret that science has known for a long time that there is some genetic component involved, a huge new study has seemingly confirmed that they’ve identified a link between DNA variations and same-sex sexual behaviour in humans.
The study first came into light when a team of researchers discovered four genetic variants across four chromosomes that seem to be linked to same-sex attraction. Unlike previous research, which has typically concentrated solely on same sex attraction in men, this study has also found a genetic link for female homosexual behaviour – the first ever discovered to date.
This study’s results were discovered after the team analysed the DNA information of over 400,000 volunteers in the UK Biobank, as well as more than 69,000 people who had given their genetic material to the private biotech company 23andMe. This data was then compared to exhaustive questionnaires covering sexual history and behaviour, which participants completed when submitting their DNA. After initially seeing the link in these two huge datasets, the team then confirmed it in three smaller studies, bringing the total number of subjects to over 490,000 people.
Previous research has linked sexual orientation in men to genetic variations in their DNA, and it seems this study has reinforced that finding, as two of the four genetic variants the team identified were specific to male sexuality. However, the other two were connected to sexuality in both men and women.
“There is no gay gene,” lead study author, Andrea Ganna states. “Non-heterosexuality is influenced by many tiny-effect genetic factors.” The team estimates their four variants account for only 8 to 12 percent of the genetics behind same sex sexual behaviour.
Recently, more research was undertaken by North Shore University in Illinois and claims to have discovered genetic markers that indicate whether or not a person is gay. Scientists compared the whole genomes of around 1000 homosexual men and 1200 heterosexual men and found there were two specific DNA regions that differed between the groups.
One of the regions dealt with a gene that plays an important role in brain development and hormone production, which could also be linked to a person’s sexual orientation. The other gene is linked to thyroid function, which is an area previously been linked with sexual orientation, according to the authors of the study. While some genetic differences were found in these areas, the researchers have cautioned that the results are “best described as speculative”, but still leave researchers a step closer to understanding how sexual preferences develop.
The study has some major advantages over previous research into the genetics of sexuality – the most obvious being the size of participants in the study itself. With nearly half a million participants overall, the findings are much more likely to be more knowledgable and accurate than those of smaller studies that would have fewer participants.
“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,” Dr Brendan Zietsch of the University of Queensland told the Australian Science Media Centre in a statement.
Although, it’s hard to say what the exact effect of these genetic variants could have on an individuals behaviour, some are already known to be associated with certain characteristics – like being linked to our sense of smell, or linked to male pattern baldness.