Well, a mutation is technically a change to the original DNA code, so it isn't inherited but it can occur during the first DNA transcription phase, or something along those lines. Or it could happen later in life, just by accident, or because of some outside influence.

Point being, I don't think a meta-human and mutant distinction technically works, scientifically, I presume meta-human simply means any abnormal human which covers people who are born with powers, or develop them at a later date, where-as mutant means anyone with a DNA mutation.

I dunno though, I've forgotten more than I ever learned, A-level biology was a long time ago.