Study finds men with older brothers likely to be gay

In 1962, a team of researchers led by American-Canadian sexologist Ray Blanchard published a study that said the greater number of brothers a boy has, the more likely he is to be gay. This was called the fraternal birth order effect. Now, researchers believe they found the biological reason behind such a pattern and it is linked to a phenomenon that happens in the womb due to the Y chromosome, which women do not possess.

Study finds men with older brothers likely to be gay