The gay gene does not exist, but the straight gene does not exist either. Sexuality is diverse and cannot be predicted with a DNA test. This is the outcome of a large international study that investigated the genetic make-up of people who have sex with people of the same sex.
There is a wide range of sexual expressions, including homosexuality and bisexuality. The results of the study were published in the renowned American journal Science. The research was conducted by an international team of researchers, including Karin Verweij and Abdel Abdellaoui of the Amsterdam UMC teaching hospital and staff of research institutes from Boston, Brisbane and Cambridge.
The researchers wanted to know if people who had sex with someone of the same sex have a different genetic make-up than people who only had sex with people of the opposite sex. The geneticists examined the DNA of more than 470 thousand Britons, Americans and Swedes who had previously donated genetic material and had answered questions about their sexual behaviour.
The researchers found five genes that, to a small extent, determine whether someone behaves homosexually, but less than one percent of the individual differences can be traced back to this. The researchers emphasize that many other genes are involved in homosexual behaviour, which together account for between 8 and 25 percent of the individual differences.
"There is no such thing as a gay gene," professor of Genetics in Psychiatry Karin Verweij of the Amsterdam UMC says. “There are most likely thousands of genes involved in homosexual behaviour, all of which have small effects and multiple functions. The genes may also play a role in other personality traits, such as being open to new experiences."
The researchers make it clear that in addition to genes, environmental influences - such as the biochemical processes in the womb - explain individual differences in sexual behaviour. The results of this study show that, on the basis of DNA, it is impossible to predict whether someone is heterosexual, gay or bisexual.
"This research confirms that genes do play a role in sexual orientation. That is interesting, but we already knew that. It was also apparent from smaller-scale studies that have been published in recent years, " COC President Astrid Oosenbrug says. “Our main concern is the fight against violence and discrimination against LGBTI people and the promotion of acceptance of sexual and gender diversity. The fact that sexual diversity has a natural cause can help us with that - for example, in banning gay conversion therapies. "
To communicate the results carefully to the public, the researchers have created a website where the results are presented: GeneticSexBehavior.info.