User blog comment:Theyokid/THE BORGIAS/@comment-1153722-20120406134744/@comment-1153722-20120408204352

The Shroud did some fucked up things. Giovanni was also able to see Brutus' memories since they both came into contact with the artifact. Perotto came into contact with the artifact just as Giovanni did. When Perotto speaks via Giovanni, it means Perotto has a temporary conscious inside Giovanni that could not be held within genetic memory. Therefore the explanation would be the Shroud, not genetic memory.

And it is never really established whether Giovanni is Perotto's son, it is only assumed as such in Project Legacy. The mystery isn't cleared up, and that is also shown in the Encyclopedia, where it is explicitly stated that he is either Perotto's or Cesare's son.