Gay, Straight, and the Reason Why: The Science of Sexual Orientation (2010; second edition 2016) is a book about the development of sexual orientation by Simon LeVay, in which LeVay argues that sexual orientation is an aspect of gender that emerges from the prenatal sexual differentiation of the brain, and criticizes Freudian and behaviorist explanations of sexual orientation. Gay, Straight, and the Reason Why received both positive and negative reviews. In 2012, it received the Bullough Book Award for the most distinguished book written for the professional sexological community published in a given year.