Mangekyou Madara/Izuna

[Gouki]

Well, it took me a while to come to this realization, but my question is, who was the catalyst for Madara/Izuna's mangekyou sharingans. We know now that the stressful/life changing event causes a mutation of the eyes: giving us a sharingan.

and then we know witnessing/killing someone extremely close to you when you have your sharingan unlocks the magekyou.

Ok, so who was it that triggered Madara and Izuna's MS. could it be their dad? because here it states that he was now the head and he had the EMS.

oh and orochi has senju cells... seems he really changed course instead of just obsessing over the Uchiha

[Hoshikaqe]

Yeh mayb His father but with the war between the senju n uchiha. Naruto leaves us open to Possibilities. N a idea of the nature of the time. * shruqs* my opinion anyway

[Reiki]

yes...maybe becos his father..but oro's body is formed from senju cells becose when he eliberated the shiki fujin seal he posesed one of the zetsu bodyes becose his body was dieing from that cut.

[the big boss]

hashirama might not know so hope for a story from madara.

[Scarlet Ninja]

From what I understand from the newer chapters, it's not the actual act of killing someone close to them. It's the emotional trauma that comes from it. I would imagine that Madara's eyes became more advanced as he fought Hashirama over and over again as he grew up. Also, most or even all of the Uchiha abandoned Madara as the war went on so the feeling of betrayal from his whole clan may have unlocked the mangekyou.
I dunno. The Big Boss has a good point though. I think later on, Madara will tell his side of the story.