There's new evidence to contradict the argument that being gay is merely a “lifestyle choice.” A new study of 400 gay men in the U.S. has found genes on at least two chromosomes that affect whether a man is gay or straight. The precise mechanisms for the genetic effects are still unknown, but scientists discovered a region of the X chromosome called Xq28, which affects male sexual behavior, as does part of DNA on chromosome 8. Still, scientist Alan Sanders says the belief that there’s a "gay gene" is an oversimplification. “Whatever gene contributes to sexual orientation, you can think of it as much as contributing to heterosexuality as much as you can think of it contributing to homosexuality. It contributes to a variation in the trait."