Is our sexuality determined primarily by our genes? Or is it shaped by the social norms and expectations we happen to be born into? This Very Short Introduction provides an accessible, thoughtful, and thought-provoking introduction to major debates around sexuality in the modern world, highlighting the social and political aspects of sexuality. It critically explores different ways of defining and thinking about sexuality and shows that many of our assumptions about what is 'natural' in the sexual domain have, in reality, varied greatly in different historical or cultural contexts. The volume also examines ways in which governments have tried to regulate citizens' sexualities in the past—through policies and laws concerning public health, HIV/Aids, prostitution, and sex education—paying special attention to the particular zeal with which women's sexuality has been policed. The volume concludes by discussing political activism around sexuality more widely, focusing on the ways in which feminists, lesbians, and gay men, as well as religious fundamentalists, have transformed our ways of thinking about sexuality in the past few decades.