Maybe Xavier was drunk, or concentrating on chatting up girls, but he really should have known that the majority of genetic variation in a typical population of individuals comes not from mutation creating new genes (as he seemed to imply), but from the recombination (shuffling) of the existing genes.
Mutations are typically immediately lethal (even before an embryo reaches maturity), or at best crippling. For example, a fruitfly with legs instead of antennae on its head does not have the benefit of any super-power!
The shuffling of the existing pack of genes is much less disruptive to an organism and much more likely to result in a more successful individual. Thus most evolution is driven by such recombination, not by mutation.