Background The explosion caused by the fusion of quantitative genetics and molecular genetics will transform behavioural genetic research in child and adolescent psychology and psychiatry. Methods Although the fallout has not yet settled, the goal of this paper is to predict the next 10 years of research in what could be called behavioural genomics. Results I focus on three research directions: the genetic architecture of psychopathology, causal modelling of gene‐environment interplay, and the use of DNA as an early warning system. Conclusion Eventually, whole‐genome sequencing will be available for all newborns, which means that behavioural genomics could potentially be applied ubiquitously in research and clinical practice. Three transformative developments for behavioural genomic research in the next 10 years are described. First, behavioural genomic research will use dimensional measures to reveal the hierarchical genetic architecture of psychopathology. A second direction for behavioural genomic research will be to investigate causa models of GE interplay. Third, polygenic scores will be used as an early warning system in childhood to predict profiles of adult psychopathology, which will eventually transform clinical practice.