By combing through genomic data of over 1 million people of European or African descent, scientists have identified genes commonly inherited across addiction disorders, regardless of the substance being used. This dataset — one of largest and most diverse of its kind — may help reveal new treatment targets across multiple substance use disorders, including for people diagnosed with more than one. The findings also reinforce the role of the dopamine system in addiction, by showing that the combination of genes underlying addiction disorders was also associated with regulation of dopamine signaling.