What's the Big Deal about Messiah Complex

After years of reading X-titles, I am still unsure what constitutes a 
mutant.  Specifically, what happens when a child is produced by one or two

mutant parents?  By definition a mutant is someone possessing attributes 
that are not passed down from his/her parents so there's a need for a
second 
term to indicate mutant offsprings.  There's been so few second-generation

"mutants" in MU that it's hard to determine whether mutant powers could be

passed down from generation to generation.  For example, Siren has the
exact 
same power as Banshee but Quicksilver's daughter is normal (In)human.

On the other hand ,they keep saying that all humans are born with
"x-factor" 
so technically every single person could become a mutant if their genes
are 
triggered.  Furthermore, they keep saying that mutants are a separate race

from homo sapiens.  A race would mean everyone within the group shares 
something in common that can be passed down to the next generation.

So what does it mean when Scarlet Witch say "no more mutant"?  No more 
mutants with human parents?  Or does it mean that existing mutants cannot 
pass down their powers to their children?