A growing number of genomic studies have generated important discoveries regarding human health and behaviour, but new research from the University of Oxford suggests that scientific advancement is limited by a lack of diversity. They show that the people studied in genetic discovery research continue to be overwhelmingly of European descent, but also for the first time reveal that subjects are concentrated in a handful of countries—the UK, US and Iceland, and have specific demographic characteristics. The authors caution that this lack of diversity has potentially huge implications for the understanding and applications of genetic discoveries.