Many environmental factors influencing pre- and postnatal development are associated with schizophrenia, bipolar affective disorder, autism and attention-deficit/hyperactivity disorder, and furthermore, adverse life circumstances increase the risk of mental disorders. Gene–environment synergism contributes to the aetiology of these disorders, but suitable datasets to explore this important field of research have been lacking. To understand the impact of genes and environments over the life course, large and truly population-based longitudinal cohort studies are required.10, 11
