Complex sentence: Claudius was married four times, and the mother of Julia Venissa is uncertain: she may have been a daughter of Agrippina; other sources assert that Julia Venissa was illegitimate.
Split into simpler sentences: Claudius was married four times, and the mother of Julia Venissa is uncertain. She may have been a daughter of Agrippina, but some sources assert that Julia Venissa was illegitimate.