So technically Wily caused that since he caused Sigma/Zero which caused the EVENTS..
Here's something interesting that I just discovered today in
an article about the MM storyline on 1UP:
"For the longest time, fans thought they had the origins of Zero sussed out, along with the truth behind Mega Man X's connection to the original series. But last year saw the Japanese debut of Mega Man Zero: Official Complete Works, an art book with a "definitive" timeline that basically exists to say that everything you know is wrong.
For years, the Mega Man/MMX connection seemed fairly clear-cut: X was a new model robot based on the original Mega Man, and Zero was created by Dr. Wily to destroy everything good in the world. That much is still true, but the common belief was that the Maverick virus was created by Dr. Wily and given to Zero. The prevailing theory: Wily figured that if Mega Man were able to destroy Zero, he'd absorb the virus when he did his usual program-copying. It's very clever! Mega Man's greatest strength would be his downfall.
Surprise: That's not how it was at all. The truth is that the Maverick virus was created by Dr. Light. That's right -- the champion of all that's good in the world was responsible for the greatest evil it ever knew.
Well, not quite. The virus was in fact a subroutine designed for X as part of his moral programming. Called the "suffering circuit," the "virus" was intended to pacify X and make him abhor violence. And it worked just fine for X; the problem was when Dr. Cain created flimsy X knockoffs. Apparently, their cut-rate circuits just weren't up to snuff and had a negative reaction to the suffering circuit's effects, making them unruly and fond of violence. Whoops!
Due to X and Zero's similar designs -- Doctors Wily and Light developed their technology together -- the suffering circuit is actually what helped Zero to reform. Meanwhile, Sigma caught the "virus" from his exposure to X -- not from Zero."
The article goes on to say that the Maverick Hunter X remakes were going to smooth out the storyline. Ah, well.