Context: Just as Rome itself claimed the favour of the gods, so did some individual Romans. In the mid-to-late Republican era, and probably much earlier, many of Rome's leading clans acknowledged a divine or semi-divine ancestor and laid personal claim to their favour and cult, along with a share of their divinity. Most notably in the very late Republic, the Julii claimed Venus Genetrix as ancestor; this would be one of many foundations for the Imperial cult. The claim was further elaborated and justified in Vergil's poetic, Imperial vision of the past.

Question: What did many Romans claim in the Republican era?
Answer: divine ancestor

Question: What style of claim did Romans favor as a link to the gods?
Answer: personal claim

Question: What deity did the Julii claim as an ancestor?
Answer: Venus Genetrix

Question: Of what were such claims of deity relations the start?
Answer: Imperial cult

Question: What author further elaborated on the imperial claim of godhood? 
Answer: Vergil