Scientists Link Brain Symmetry, Sexual Orientation

A scientist with a brain scanner could figure out your sexual orientation based on the symmetry of your brain, new research from the Stockholm Brain Institute hints.

Using MRI scans of gay and straight men and women, the researchers found that people who liked women -- heterosexual men and homosexual women -- had larger right brain hemispheres, while people who liked men -- heterosexual women and homosexual men -- had symmetrical brains. As seen in the image, MRI and PET scans showed a similar pattern in two specific regions of the brain, the right and left amygdalas, which are thought to control fight-or-flight reactions.

"The results cannot be primarily ascribed to learned effects, and they suggest a linkage to neurobiological entities," the researchers, led by Ivanka Savic, write in a paper that will be published in the Proceedings of the National Academy of Sciences tomorrow.

While the research is suggestive, it does not address how such brain differences come to be, although the researchers noted that there could be genetic, environmental and/or sex hormonal factors.

via Wired