If the 4th is naruto but reborn how could he have 2 bodies at the same time -_-.
I think that naruto is his son because if you watch the first ep you will see that he was late, and he sealed the kyuubi in a baby who was just born. So the 4th cant be naruto.
I think he was late because of the birth of naruto.Its more likely that naruto is his son.