Researchers at the University of California, Los Angeles, have reported that sexual identity and orientation is determined by genetics according to their findings released on Monday. The findings could mean that sexuality, including homosexuality and transgender sexuality, are not a matter of choice.
Dr Vilain and his team discovered 54 genes in mice, which they say may explain why male and female brains look and function differently, and control sexual orientation as well as the development of the sexual organs. The genes are produced in different amounts in male and female brains. Eighteen were produced at higher levels in the male brains and 34 were produced at higher levels in the female brains.
"Our findings may explain why we feel male or female, regardless of our actual anatomy," said Dr Vilain. The scientists plan to conduct further studies to determine the specific role for each of the 54 genes they identified.
For example, the two hemispheres of the brain appeared more symmetrical in females than in males. According to Dr Vilain, the anatomical difference may explain why women can sometimes articulate their feelings more easily than men.
The findings published in the latest edition of the journal Molecular Brain Research also rebuts 30 years of scientific dogma that the hormones, estrogen and testosterone, alone were responsible for differences between the male and female brain. Historically, the hormones were also thought to be responsible for sexual orientation.
While stressing the study was "not about finding the gay gene," Dr Vilain said "the first human implication will be to understand transexualism, which is different than homosexuality."
Dr Vilain's research also brings better understanding to transsexuals and offers a tool for gender assignment of babies born with ambiguous genitalia.
"If physicians could predict the gender of newborns with ambiguous genitalia at birth, we would make less mistakes in gender assignment," Vilain said.
Dr Vilain added that finding the exact gene that results in homosexuality would require considerable more research and added that if future research does determine conclusively that homosexuality is genetic and not a choice, the implications would be huge.
"If it's not a choice, you can't have the typical conservative argument that says you choose this lifestyle so you have to bear the consequences and society has no reason to basically give you any rights because you choose to be an outcast," he said.
"If you can't do anything about it, therefore you should have all the rights to be integrated into society and have the same rights as heterosexuals in terms of marriage and the rights to inheritance."
At the same time, he worries that parents could misuse prenatal diagnoses and decide to abort a fetus if it was not going to have the type of behaviour they wanted, he says.
Last week, British psychologists from the University of East London and from King's College also said they have found strong evidence to support the theory that a person's sexuality is "hard-wired" into the brain before birth.
Do you think you are 'born this way?' What implications do you think the findings of such studies would have on society's perception and/or acceptance of gays, lesbians and transgendered people? Share your opinion in the forums.