Scientists at the Karolinska Institute studied brain scans of 90 gay and straight men and women, and found that the size of the two symmetrical halves of the brains of gay men more closely resembled those of straight women than they did straight men. In heterosexual women, the two halves of the brain are more or less the same size. In heterosexual men, the right hemisphere is slightly larger. Scans of the brains of gay men in the study, however, showed that their hemispheres were relatively symmetrical, like those of straight women, while the brains of homosexual women were asymmetrical like those of straight men. The number of nerves connecting the two sides of the brains of gay men were also more like the number in heterosexual women than in straight men.