Direct lineage conversion offers a fast and simple method to study mature neurons in vitro, but its utility for investigating neurodevelopment has remained unclear. Yichen Li and Justin Ichida preview research by Chanda et al. (2019), using Ngn2-induced neurons to elucidate the pathogenic mechanisms of the teratogenic compound valproic acid. To read the preview, visit sciencedirect.com/science/article/pii/S1934590919302693?via%3Dihub#bbib2.