Since all glial cells share the same origin, most cerebral gliomas tend to be thought of coming from astrocytic origin, as they closely resemble astrocyte morphology. Here the authors provide evidence that astrocyte tumors of X-linked origin among others are in fact of ependymal, rather radial, glial cells. Juvenile brain tumors are mainly removed by surgery, so determining a genetic origin as well as the specific cell type can lead to targeted drug therapeutics.