Researchers have found that three different autism risk genes actually affect similar aspects of neuron development and the same neuron types, although each gene acted through unique molecular mechanisms. Additionally, a person's specific genomic background fine-tuned the genes' effects. The study was conducted using miniature 3D models, or 'organoids,' of the human cerebral cortex, the part of the brain responsible for cognition, perception, and language. The results advance our understanding of autism spectrum disorder and are a first step toward finding treatments for the condition.