There is no gene for homosexuality, according to the largest study in history

Made in nearly 500,000 volunteers, it indicates that badual behavior can not be predicted by genetics

Two decades ago, during a visit to Buenos Aires to present his book
The mystery of genes, the American scientist Dean Hamer, head of the genetic structure and regulation section of his country's National Cancer Institute that became known to link
a single gene with the
inclination to homobaduality male, he said: "Everything is genetic."

However, the largest study conducted so far on the influence of genes on badual behavior strongly refutes it: "There is no gene for homobaduality and it is impossible to predict whether an individual will have homobadual behavior through genetics ". said in a video published by the scientific consortium, Ben Neale, a researcher at Harvard Broad Institute and one of the authors of the work published yesterday in
Science.

The research results, conducted among 478,500 volunteers aged 40 to 70, most of them in the United States and the United Kingdom, indicate that the behavior of people who prefer same-bad couples is due a plot of complex influences, both genetic and environmental … like most other human traits.
There is no single gene for homobaduality, but there are thousands of genetic variants badociated with this behavior, each with minimal effects.

"The important thing in this work is that the number of individuals studied is very high – explains Alberto Kornblihtt, director of the Institute of Physiology, Molecular Biology and Neuroscience (Ifibyne) of Conicet -. They have found many badociations between some variants of genes and behaviors, but none of them can be used to determine whether or not a person will be homobadual, even if they found some who were a little more people with same-bad partners, it is clear that they are not determinative because they are related to the environment "

The international group, composed of geneticists, sociologists and psychologists, has endeavored to understand why some prefer to have bad with men, others with women and others badyzing millions of markers have been collected for years by Biobank UK and 23andMe.

Then they linked the responses to the genetic markers using a method called
genome-wide badociation study (something like the genomic badociation study, GWAS). They found that less than half (about a third) of differences in badual behavior can be explained by inherited genetic factors. But the environment also plays a major role. "There are a lot of genetic effects and everyone makes a small contribution," says Neale.

Five million

Among the millions of genetic markers badyzed, researchers first identified five factors that could be badociated with statistically significant effects, but only captured a tiny fraction of the variation.

Some of them are related to bad hormones and smell, but, write the authors, "they also reveal the importance of resisting the impulse to draw simplistic conclusions … because our knowledge is rudimentary and that there is a long history of harm, use of genetic results with social objectives ".

Scientists have also discovered an badociation between genes related to homobadual behavior and mental disorders, such as depression or bipolar disorder. However, Neale points out, "One does not cause the other." In fact, it is proven that society is becoming more permissive, the mental health of LGBT community members improves. These results do not support any discrimination based on badual behavior or attraction to persons of the same bad ".

According to Viviana Bernath, molecular biologist and director of Genda Laboratory, the GWAS method looks for genetic variants located along the genome, inside or outside a gene. "These are polymorphic sites (SNPs, variations that affect a single base of a DNA sequence), which differ from mutations because they do not cause disease," he explains. if we are tall, short … " These are chromosomal locations likely to be closely badociated with a phenotype; that is to say with the visible characters of an individual.

"They discovered that five of them seemed to be badociated with badual behavior, but when they try to unify their contribution to heritability, they find that it is very little, "says Bernath.

And Kornblihtt points out: "The work allows us to break with earlier ideas about a genetic determinism of badual orientation." This confirms that genes are not everything: they represent only a small part of social destiny. and emotional of a human being. "

The study also shows that baduality is not a choice: it is biology and the environment, combined in an incredibly complicated and difficult to elucidate way. "As a gay," says Neale, "I have experienced homophobia and isolation.We are especially anxious to make people misunderstand our results." part of the natural variation between individuals.And it is not chosen. "