I thought the reason that Sanctus said he had the blood of Sparda was because of his devil arm...(which I believe is Vergil's spirit). It would make sense because Vergil's spirit does run throughout Nero's body. (as you can see when you release Nero's 'Devil Form')
I seriously doubt Nero is blood related to Dante, Vergil or Sparda. He is related to them somehow, but how he is related, we do not know....yet.
I seriously doubt Nero is blood related to Dante, Vergil or Sparda. He is related to them somehow, but how he is related, we do not know....yet.