I don’t think Beast’s intelligence is part of his mutation. Geniuses are not exempt from chromosomal abnormalities.
And, yes, I think a mutant could be one without realizing. It’s been awhile since I’ve read them, but I do vaguely recall Professor X finding several mutants (using Cerebro) who had no clue about their latent abilities. Like Blackberry said, some required a trigger of sorts.
Though are you asking about mutants that haven’t been triggered yet? Or are you asking about mutants who have enhanced abilities (e.g. increased speed, enhanced hearing) versus supernatural abilities (e.g. flying, telekinesis)?
I’d say that would depend on the level of their mutation. Can they run 1.5x faster than the average human (Olympic athlete) or 150x or 1,500,00x faster?
Also, are they freaking morons? Idiots aren’t exempt from chromosomal abnormalities either.