For centuries, humanity has operated within the binary understanding of gender - that individuals must identify strictly as male or female. But in recent years, the concept of non-binary gender has emerged, challenging the traditional binary framework and arguing for the validity of identities outside male and female categorization. In this groundbreaking new book, Henley systematically dismantles the case for non-binary gender and exposes it as a fallacy detached from scientific, cultural, and ethical realities. By rigorously examining non-binary gender theory through the lenses of biology, psychology, sociology, medicine, and more, Henley reveals the lack of evidence supporting identities outside the gender binary. They delve into the biological basis of the male-female dichotomy, analyze social and cultural factors perpetuating non-binary mythologies, and explore the dangerous implications of embracing subjective gender identities. Armed with compelling arguments grounded in science and logic, Henley debunks the concept of non-binary gender as biologically incoherent, psychologically confusing, socially disruptive and culturally unsupported. They advocate a return to fundamental truths about human nature to create a society in which objective facts, not subjective identities, serve as the bedrock for gender understanding. Incisive and intellectually uncompromising, this book will forever change how we view gender and its role in both individual identity and social organization. The case against non-binary gender has found its definitive voice.