When is sex abnormal and when is it dangerous? A multi-disciplinary approach that includes sociology, anthropology, history, and philosophy provides an understanding of how cultural norms have shifted over time and the implications of these shifts. Proposed definitions of "abnormal" and "dangerous" and their impact on public policies and practices are evaluated, as are our contemporary assumptions about sex and sexuality and the consequences of those assumptions. This should also serve as a toolkit for how to answer questions about sexuality such that readers can apply this model as new questions and social concerns about sex arise in the future.