In addition, they have found "a genetic correlation" between homosexual behavior and depression

GAYLES.TV.- An international team of scientists has conducted the largest study on the influence of genetics on sexual behavior. The work is 100 times greater than the last previous study done and almost 500.000 people have been analyzed. The most telling conclusion is that there is no single gay gene, but rather many genes that influence the likelihood of a person having same-sex partners.

There is no gene for homosexuality or heterosexuality or intelligence. They are very complex behaviors, probably linked to hundreds or thousands of genetic variants distributed throughout the genome.. The combined effects of these thousands of genetic variants today unknown would add up to those detected influences of 33% or 8% -25%, depending on the type of analysis.

A first analysis showed that close relatives are more likely to exhibit similar sexual behaviors. The authors estimate that one third of the differences observed in the sexual behavior of these relatives can be explained by inherited genetic factors. The rest of the differences are due to the so-called environmental factors that do not have to be related to education or culture. They could be non-genetic biological effects or the prenatal environment in the uterus

Of the five variants identified, two are shared by men and women, two are male and one is female. Its individual effect is so small that it can only be detected in investigations with hundreds of thousands of citizens. For example, 4% of people with a variant in the rs34730029 position of the genome exhibit homosexual behavior, compared to 3,6% who do not have that variant. In order to identify more relevant differences in DNA, millions of people will have to be studied.

Ben Neale, associate professor in the Analytical and Translational Genetics Unit of the Massachusetts General Hospital, who worked on the study published in Science, declared: «Genetics is less than half of this story about sexual behavior, but it is still a very important contributing factor. There is not a single gay gene, and a genetic test to determine if you are going to have a homosexual relationship will not work«.

"Genetic correlation"

In addition, researchers have found "a genetic correlation" between homosexual behavior and some personality traits such as the feeling of loneliness, openness to new experiences and risky habits, such as smoking and marijuana use. They have observed a genetic correlation with some mental health problems such as depression or schizophrenia. On a scale from 0 to 1, in which zero means that genetic influences do not overlap in two different traits, depression reaches 0,44 in women and 0,33 in men, while schizophrenia reaches 0,17 in women and 0,13 in men.