Naruto Shippuuden Episode 253

[DarthEnderX]

Rinnegan concretely being originally Madara's is bullshit. Like I said before, there's no way Madara knew Nagato back when those three were just orphans wandering around and then teached by Jiraiya. Either he had some role in teaching Nagato later or he's one of the megalomaniac egoists, who think along the lines of: "I'm the greatest Uchiha ever so all special eyes belong to me."

I think he might have orchestrated the events that led to the Rinnegan awakening.

Knowing that Madara is capable of mind controlling a Kage/Jinchuuriki, it's entirely possible that he's controlled certain people that led to the situations that caused the Rinnegan to awaken.

In fact, it's entirely possible that the war that cause the shitty conditions that formed all of Nagato's development could have been the result of Madara mind controlling someone like Hanzo.

Since his original appearance of the Rinnegan happened when his parents were killed, then awakened permanently when they were attacked later, and finally he entered his final state summoning the dragon god statue when Hanzo had Yakuhito killed, then if Madara orchestrated that war, he could consider himself the reason for the Rinnegan existing. He may have even caused that war IN ORDER to give rise to the Rinnegan.

Like I said before, there's no way Madara knew Nagato back when those three were just orphans wandering around and then teached by Jiraiya.

I'm not so sure of that. After all, Madara seemed to know that Nagato was an Uzumaki, when even Nagato himself didn't seem to know that. If the Uzumaki clan was the clan that was capable of awakening the Rinnegan, it wouldn't surprise me if Madara had been tracking Nagato's parents before he was even born.

[Kraco]

If all that was true, Madara himself must have belonged to the Clan Aizen, not Clan Uchiha... Generally speaking, though, he might have been controlling some of the culprits for the war, and it's thus, generally speaking, possible to claim he was at least partly responsible for the awakening of Rinnegan. What comes to Nagato's origins, he would have had all the time in the world to find that out later with his sources.