I've come to the conclusion that Smurfs are a magical construct that reproduce through cloning. This is based on there being no original females, Smurfette and Sassatte being golems made by Gargamel and the Smurflings respectively. There is another Nana Smurf but her background is sketchy at best, possibly a failed plan by Balthazar(godfather of Gargamel and probably where he got the spell to make Smurfette from). Also this explains the single facet personalities of the Smurfs, as there is only one perfect clone made per generation. Baby Smurf being the perfect clone of Papa as Papa is to Grandpa Smurf(also the only ones with the ability to use magic.)