With the help of cerebral organoids, scientists were able to ascertain that tuberous sclerosis, a rare neurodevelopmental genetic disorder, arises developmentally rather than only genetically. With these patient-derived laboratory models of the human brain, they pinpointed the origin of the disease to progenitor cells specific to humans. The findings further show that the pathology of diseases affecting the human brain could only be well understood using human-derived brain organoid models.