A genetic basis for homosexuality has been all but proved, yet Darwinism, the most widely accepted evolutionary theory, emphasises successful reproduction. How do we explain a lifetime preference for non-reproductive sex? Whilst social constructionism offers explanations in terms of social learning and cultural preferences, the body of evidence for a genetic predisposition to homosexuality grows. Social learning argues that homosexual sex is merely misdirected and therefore futile, but far from dying out it continues through the ages and is found in different cultures. What if there was an evolutionary advantage to homosexuality? Straight Science? Homosexuality, Evolution and Adaptation dares to ask such questions.