Hm, well, y'see, Inafune himself took part in the creation of the book and the information has to do wif both the X and Zero series. Also, I hear it goes along somewhat better wif the MHX games than the original X games, however both are the same X series, and the plot is the same in the end. Methinks whether it was thought up years after or not is irrelevant to the validity of the information.
As fer ze Wily relation to X series thinger, I guess ye've a point there. Personally I've no clue when he was thrown into the mix in the games, having played only X, X8 and Command Mission outta the X series. Possibly X2 too, but can't remember if I have anymore.
Well, ditching the Wily part then, it still contains the bit about X being the origin of the so called maverick virus. According to my understanding, he was given a sort of "worry circuit" (not necessarily a physical circuit but a thought pattern maybe) that causes him to worry about siding with either humans or reploids in relevant situations, and Light put him into the stasis fer 30 years so that it'd most likely run simulations that included this circuit and "trained" X in controlling himself wif the thinger. Since after all, if he couldn't handle it, well, yeah. I doubt I need'ta finish that sentence.
Now, Cain ditched this process wif his reploids, meaning not everyone had the willpower to be able to decide when situations wif the circuit came and went crazeh. Some on the other hand could clearly decide, but chose reploids, which caused humanses to label 'em as a danger fer humanses. Now, Sigma was all strong-like and capable of not going loco or choosing reploids, until he fought Zero. Zero was carrying a virus, that then jumped to Sigma in their fight and messed wif his thought process and turned him maverick later on. The virus also mish-mashed wif Sigma's DNA code to mutate into ze Sigma Virus. The Maverick Virus? No such thing, only Sigma and Zero Virii, and Nightmare Virus later on too.
Also, fun fact: the worry circuit effect jumped from someone, Sigma or X, I'm not sure which, to Zero, and somehow calmed him down. Zero had been but a raging killer, however he had normalness inside him, only it had been blocked by stuffs Wily did, but the transplantation of the Worry Circuit whatever phix'd that and we got a nice Zero. Then Zero went wandering fer a while to improve and unknowingly infected a load of other reploids wif virusness.
... Erm, ignore the fruit loop talkings of mine there, it just kinda comes automatically. XP
Also, that's the most relevant info that I can remember off the bat, ye can choose if'n ye wanna add it along or not. If'n ye do choose to do so, I recommend checking RPM fer more information on the thinger, since this is from my vague memory and most likely not the 100% accurate version. >_>
