Men who have a brother have a higher chance of becoming gay

Men with an older brother are more likely to become gay and the cause of the problem is formed before birth.

This is the result of a team of researchers led by Anthony Bogaert, a professor at Brock University's Department of Public Health and Psychology, published in PNAS, a publication. Weekly science published by the US National Academy of Sciences.

There are many different factors that need to be considered to determine someone's sexual orientation. But in this case, the researchers found the existence of an aspect related to a protein that binds to the mother's uterus (chromosome not available) in the womb.

The researchers suggest that the protein associated with the Y chromosome may have entered the mother's blood when pregnant with her first child. At that time, the mother's body will immediately detect the protein and create antibodies to defend itself. After a while, this antibody has accumulated a certain amount, this woman is pregnant with another baby. Most likely, antibodies that cross the placenta now enter the baby's brain. And this may be the cause of the brain's functions to change, which in turn tends to develop a sense of attraction in the male fetus.

Previously, there was a study that yielded similar results, a man with the probability of becoming gay and attracted to other men was higher if there were many brothers. In 2006, a study showed that the proportion of a gay man would increase by about one-third if there was an older brother, but then scientists could not explain this phenomenon.

Professor Bogaert and his colleagues conducted an experiment for 20 years with the participation of a small group of 142 women, 12 men between the ages of 18 and 80. Determined results The concentration of protein antibodies named NLGN4Y in their blood samples showed a higher concentration of NLGN4Y in women with more boys and homosexual children than women without a son or a son but a cent. normal sexual orientation.

Before announcing the results, they did a lot of research to find out the cause of that phenomenon. Accordingly, a man is likely to become gay even if he does not grow up next to him and this does not happen if the family has an adopted brother. Therefore, researchers have thought of a biological mechanism related to the mother.

However, this study cannot point out why some men become asexual or bisexual.