This document was originally created by Mondo and was on his great page which is no longer around. These theories were taken from user polls that Mondo conducted.
(1) The Combination Theory (most believable)
Monet is the combination of her twin sisters OR the combination of her sisters with her mother (less likely). The change in Monet's attitude throughout the 30 issues is what hints at this theory. She has shown a side which is extremely intelligent, able to solve complex tasks/problems in life. And she has shown a side which is childish in nature. This could perhaps be the two different personas of the twins in control of Monet at different times. The variety of powers that she posseses are the powers from both siblings.
A struggle seems to be happening within Monet's body. When she shifts into her catatonic stupor, the persona's inside her are fighting for control OR talking with each other. She has spoken in the plural tense ("us") before, hinting that she is more than one being. Another answer could be that one of the twins is autistic and the other is normal. The shift in each twin's characterisitcs causes Monet to act strangely.
In the next issue of GenerationX, it will be Spittsville for Monet.
(2) The Parasite/Absorption Theory
It is possible the parasites run in the family. Monet could be an emplate just like her brother. Her ability to feed off of other mutants could be the answer as to why she has so many different powers. Monet could also have a power that is similar to Rogue's. She could have absorbed certain powers/persona's when she became a mutant.
If Monet is an emplate, then she is hiding her true form by taking on the appearance's of those she has fed on. On the other hand, if she has an absorption type power, she has somehow taken the persona's and characteristics of her victims similar to the way that Rogue does.
Monet is really a mutant parasite with psychic powers. Each time her current body is about to die, she moves her mind to another one. She chose Monet. Monet has all the physical powers and is autistic, but M is slowly learning to deal with it.
Monet's can receive the powers of a dead mutant for a limited amount of time. M first received her strength, flight and invulnerability when Ms. Marvel died, later other powers as the mutants died . In recent issues M has showed to be LOSING her powers.
Monet is an outworldly entity that will emerge out of it's mutant host.
Monet has the ability to make herself as perfect as she wants. Everytime she goes autistic, she gets a new power or improves her powers.
Monet is loosing her powers slowly because she has contracted the legacy virus.
Monet is really an Emplate who has eaten a shapeshifter to hide her real appearance. She has eaten all the mutants that would give her the powers she desires and not end up looking like big brother Marius.
And the twin theory is correct, which was the number one answer as to what Monet's secret was. Not much was revealed in Generation X #31, but we did take a quick glimpse at the twins. Who was the first to learn about Monet's secret? Synch.
As the fight between the Sentinels and the students came to an end, Monet told Synch, to use his aura to synch to her power of invulnerability because the Sentinels were preparing to fire at the two and eliminate them. Synch does what she says and realizes what Monet is hiding. She tells him to save it for later and the two survive, but are knocked out seconds later by the explosion set off by Gil to destroy the Sentinels.
When Synch awakens, he uses his aura to find his wounded teammates. Who does he find first, Monet and uhm, Monet. Two child-like versions of Monet, which are identical in looks. The twin theory seems to be the answer to who Monet really is. The next question is who these twins are, what powers do each of them have and what will GenerationX do now that they have two Monet's to deal with?