Coeliac disease is strange: unlike most other autoimmune conditions, we know exactly what causes it and dietary management is straightforward. However, there remain unanswered questions about the relative contributions of environment and heredity, and importantly, whether population screening to identify those at risk is worthwhile. Also, major differences in prevalence have been observed between populations, even those that are ethnically similar within Europe, suggesting a contribution from environmental factors. To add to the confusion, since serological testing became widely available, we have known that the prevalence of positivity to tests such …