Book excerpt: An essential guide to this major contemporary issue, Consanguinity in Context is a uniquely comprehensive account of intra-familial marriage. Detailed information on past and present religious, social and legal practices and prohibitions is presented as a backdrop to the preferences and beliefs of the 1100+ million people in consanguineous unions. Chapters on population genetics, and the role of consanguinity in reproductive behaviour and genetic variation, set the scene for critical analyses of the influence of consanguinity on health in the early years of life. The discussion on consanguinity and disorders of adulthood is the first review of its kind and is particularly relevant given the ageing of the global population. Incest is treated as a separate issue, with historical and present-day examples examined. The final three chapters deal in detail with practical issues, including genetic testing, education and counselling, national and international legislation and imperatives, and the future of consanguineous marriage worldwide.