Not Clearly Pro or Con to the question "Is Sexual Orientation Determined at Birth?"
"Categories of sexual orientation include homosexuals - gay, lesbian - attracted to some members of the same sex; bisexuals, attracted to some members of more than one sex, and heterosexuals, attracted to some members of another sex. Orientation is influenced by a variety of factors, including genetics and hormones, as well as unknown environmental factors. Though the origins of sexuality are not completely understood, it is generally believed to be established before the age of five."
"Terms and Definitions Related to Sexual Orientation and Gender Identity," Jewish Mosaic website (accessed Apr. 16, 2007)