Gay peoples' brains share similar characteristics to those of the opposite sex, a new study says.
Researchers found resemblances in the brain's physical structure and size as well as the strength of neural connections among gay people and straight people of the opposite sex.
In some ways the brains of straight men and lesbians are on similar wavelengths, the research suggests. Likewise, gay men and straight women appear to have similar brains, in some respects. The findings are new evidence that homosexuals may be born with a predisposition to be gay.
"[Our] data are more difficult to explain by a specific learned behavior related to … sexual orientation," study leader Ivanka Savic, a neuroscientist at the Karolinska Institute in Stockholm, Sweden, said in an email.
Past studies have shown that brain activity linked to sexual behavior differs between homosexuals and heterosexuals. But this study is the first to show that the cerebral networks themselves are also different, Savic said.
Fight or Flight?
Differences both in the brain activity and anatomy were observed in a study involving 90 men and women, including homosexuals and heterosexuals of both genders.
The researchers monitored neural activity in the brain by charting blood flow.
The scans were carried out when the volunteers were resting and exposed to no external stimuli.
Researchers focused in particular on the amygdala, an almond-shaped structure inside each brain hemisphere associated with processing and storing emotions.
(See pictures inside the human brain.)
In homosexuals, brain activity most closely matched that of heterosexuals of the other sex.
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