Granted, I'm sure this has been asked and/or figured out before, so do pardon me if this eggs you the wrong way.
If you start a game with a supernatural, like a fairy, and then tune the population control so that no fairies will occupy your town, can you still produce fairy nooboos? Likewise with all of the other supernaturals. I'm not going to lie, it would be very cool to be the only witch in town.