THE US: The brain, not the genitals, could be the determining factor in whether a person is male or female.
US scientists have discovered that before male or female mice develop sex organs in the womb, their brains may already be wired to be a particular sex. If the same holds true for humans, it could help to determine the "brain sex" of babies born with ambiguous sex organs, the New Scientist magazine said.
Biologists believe embryos develop ovaries and become female unless a gene called SRY on the Y chromosome switches on and testes are developed instead. "But in a study of mice, a team at the University of California, Los Angeles, has now found that males and females show differences in the expression of no fewer than 50 genes well before SRY switches on," according to the magazine.
Mr Eric Vilain, the head of the UCLA team, said three of the genes are dominant in females and four in males, but they still need to determine whether the genes influence brain sexuality in mice and whether the same thing occurs in humans.
"But if the findings are confirmed, they could one day yield blood tests that allow doctors to establish the brain sex of babies born with genitalia that share features of both sexes." - (Reuters)