User blog comment:Madman97/The Aedra Vs. The Daedra theory/@comment-3025184-20131010203442/@comment-11345660-20131011053415

Well, in any case, Akatosh tells you himself he is first born of Akatosh. If he tells you himself, then its proven. I think he would know if he was Akatosh or not, and if he was, the Dragonborn shouldn't have been able to defeat him.