BBC NEWS | Health | Scans see 'gay brain differences'
The brains of gay men and women look like those found in straight people of the opposite sex, research suggests.
The Swedish study, published in the Proceedings of the National Academy of Sciences journal, compared the size of the brain's halves in 90 adults.
Gay men and straight women had halves of a similar size, while the right side was bigger in lesbian women and straight men.
A UK scientist said this was evidence sexual preference was set in the womb.
A further experiment found that in one particular area of the brain, the amygdala, there were other significant differences.
In heterosexual men and lesbian women, there were more nerve "connections" in the right side of the amygdala, compared with the left.
The reverse, with more neural connections in the left amygdala, was the case in homosexual men and straight women.
In other words, the brain network which determines what sexual orientation actually 'orients' towards is similar between gay men and straight women, and between lesbian women and straight men.
