It has long been clear that a person’s sexual choices – whether they prefer male or female sexual partners, or both – are influenced by his or her genetic makeup.
The most direct evidence of this is that identical twin couples are more likely to have the same sexual preference as those with a similar genetic makeup, compared to non-identical twin couples who share only about 50% of their genetic makeup. to.
What is elusive is knowing certain genes, or genes. A 1993 study found that male sexual preference was influenced by a particular gene on the X chromosome, which the media naturally called “gay men.”
However, a subsequent study that did not repeat this conclusion and subsequent follow-up yielded mixed results.
The problem was that these studies were too small to draw reassuring conclusions. There are millions of parts of our DNA which usually vary between people.
This means that finding genes associated with sexual preference is like finding a needle in the Histac.
Therefore, an international team of researchers, which I led, began to address this problem. Our results have been published in science.
Our approach was simple: brutal force. The rest is the same, the bigger the study, the more confident we are in the result.
So instead of taking a sample of a few hundred or several thousand individuals – as in previous genetic studies on sexual preference – we used a sample of about half a million people.
To obtain such a large sample, we used the data collected as part of extremely large-scale projects.
These data included DNA and responses to questionnaires from UK participants (as part of a UK biobank study) and the United States (part of the data collected from 23andMe’s commercial grandfather clients, to respond to research on sexuality was agreed).
The downside to using these broad data sets is that studies were not specifically designed to find genes for sexual preference, so we were limited to questions asked by participants about their sexual behavior.
For both UK Biobank and 23andMe, participants reported whether they had a similar sexual partner.
A person’s DNA basically contains millions of code characters, and the letters vary between different individuals.
Therefore, to shorten a complex story, the next step was to test at each DNA site whether the message was more common in participants who reported same-sex partners only reported heterosexual partners.
Not one gene but many
We have found that there are no “gay genes” – instead, there are many genes that affect a person’s chances of having the same sex.
Individually, each of these genes has very little effect, but their combined effect is significant.
We can be statistically confident about five distinct DNA sites; we can also confidently declare that there are hundreds or even thousands of other places that play a role, although we cannot identify all the points where they are.
Participants in the 23andMe dataset not only answered questions related to their sexual behavior, but also attraction and identity.
Taking all the genetic effects combined, we showed that the same genes differ in same-sex sexual behavior, gravity, and identity.
The few genes that we can be sure to give evidence about the biological rules of sexual preference.
One of these genes, in addition to being associated with homosexual sexual behavior in men, was also associated with male baldness.
It also possesses a gene involved in gender discrimination – the process of masculinity and the biological masculinity of men and women, respectively.
Sex hormones are involved in both baldness and sexual discrimination, so our discovery means that sex hormones may also get involved in sexual preference.
Other findings exacerbated severe complexity in biology, demonstrating sexual preference.
First, genetic effects only partially overlap between men and women, suggesting the biology of homosexual behavior in men and women.
Secondly, we have demonstrated that, at the genetic level, there is no single continuum of homosexuals to the rectum.
There are likely to be genes that conflict with the appeal of homosexuals and genes that predict the sex of the opposite sex and differ independently.
Given the complexity of genetic effects, we cannot make a meaningful estimate of a person’s priority from DNA – and that was not our goal.
Scientific results are often complex, and easily distorted in the media.
Sexual preference has a long history of controversy and general misunderstanding, so it is particularly important to convey an accurate and accurate picture of our results.
But people want black and white answers on complex issues.