Why are some people gay?

No one knows for sure why some people are attracted to the same sex and not the opposite sex. Many scientists believe we’re getting closer to an answer, though.

• According to researcher Simon LeVay, the scientific evidence suggests our sexual orientation is fixed at birth, influenced in part by both genetics and hormone levels during the mother’s pregnancy.
  
  In his book Gay, Straight, and the Reason Why, LeVay writes: “Sexual orientation…emerges from the prenatal sexual differentiation of the brain. Whether a person ends up gay, straight, or bisexual depends in large part on how this process of biological differentiation goes forward, the lead actors being genes, sex hormones, and the brain systems that they influence.”
• In the mid-1900s, other theories were popular, including psychologist Irving Bieber‘s belief that same-sex attraction resulted from bad parenting. This influenced Christian writer Elizabeth Moberly, whose 1980s theory of a “reparative drive” helped fuel ex-gay conversion attempts (sometimes called “Reparative Therapy”). These theories are now widely considered discredited.

For more on this, see our article on “Is it a choice?”