The field of epigenetics is revolutionising our understanding of how environment shapes our genes. Dr Susan Prescott, a leading childhood immulogist, shows how the application of epigenetics through Developmental Origins of Health and Disease (DOHaD) is changing scientific research and public health. A poor start to life is associated with an increased risk of disorders throughout life, including cardiovascular disease, obesity, type 2 diabetes and metabolic disturbances, osteoporosis, chronic obstructive lung disease, some forms of cancer and some mental illnesses. DOHaD has significant implications for many societies and for global health policy. Dr Prescott explains the research and shows how a focus on early life in health promotion, the exchange of kwledge between policymakers, clinical and basic scientists and the wider public, and education and training, will build capacity to assist a healthy start to life across populations.