User blog comment:D. Cello/Assassinews 10/11 -- Desmond's Ancestry Revealed/@comment-2076716-20111120040407

I reckon that its one side of Desmond's family is Altaïr's while the other side is Ezios either that or imprinting but considering that AC had memories from Altaïr's that Ezio probably hadn't seen and that warren said it was in Desmond's DNA then the family one seems the more plausible