ABSTRACTHow schizophrenia (SZ) is maintained at roughly 1% of the population despite diminished reproduction is one puzzle currently facing researchers. De novo mutations were first proposed over half a century ago as a source for new SZ genes. Current evidence linking advancing paternal age to SZ risk makes revisiting this hypothesis important. Advancing paternal age is the major source of new mutations in the human population. This article will examine potential mechanisms whereby parental age may impact new mutations, as well as review recent data supporting such a hypothesis.