Con to the question "Is Sexual Orientation Determined at Birth?"
"The stages of psycho-social development toward adult heterosexuality are clearly demarcated, known and understood by developmental psychologists, and are so obviously learned that heterosexuality is clearly not genetically mandated. Surveys of adult homosexuals show conspicuous deficits in several of these developmental stages - showing that homosexuality is cultural and environmental rather than genetic."
Experts PhD's in psychology, without significant post-doctorate involvement in human sexuality issues, and PhD's in fields other than psychology, and MA's with significant post-graduate involvement in human sexuality issues. [Note: Experts definition varies by site.]