Pediatric and adult kidney tumors differUnderstanding tumor origins and the similarities and differences between organ-specific cancers is important for determining treatment options. Younget al.generated more than 72,000 single-cell transcriptomes from healthy and cancerous human kidneys. From these data, they determined that Wilms tumor, a pediatric kidney cancer, originates from aberrant fetal cells, whereas adult kidney cancers are likely derived from a specific subtype of proximal convoluted tubular cell.Science, this issue p.594