It's a theory that makes sense, I think. Horrifying sense!
I can forgive it with vampires I think because I don't like vampirism-as-virus. I like spooky demons and magic. So there has to be an element of possession, which suggests personality(/mind) being not entirely attached to/dependent on the brain itself.
With Kryptonians, the brain maturation seems like it should have more of an impact.. Eee.