The Kraepelinian dichotomy – the broad division of major mood and psychotic illnesses of adulthood into schizophrenia and manic depressive illness (bipolar disorder) – has been enshrined in Western psychiatry for over a century and continues to influence clinical practice, research and public perceptions of mental illness. There have been several important research findings in genetics over the last 5 years that will help to improve understanding of schizophrenia and radically change the way we think about its relationship with other major psychiatric disorders. This article will provide a brief introductory overview. The aim is to avoid being technical, to get across major points and, hopefully, to whet the appetite so that some readers will want to look at other papers. This article is based on an editorial published last year in the British Journal of Psychiatry.