ianus indicates the original family  name after an adoption, as a result of which the adoptive son  received the full name of the adoptive father. Accordingly, C.  Octavius changed his name to C. Iulius Caesar Octavianus after being  adopted and made sole heir in his grand uncles will (44 BC). As a  matter of fact, the future emperor did not like and never himself  used the epithet Octavianus pointing at his not being born a  patrician.