According to the bande-dessinée "La Schtroumpfette", by Peyo (Éditions Dupuis, 1976), the smurfette was created by Gargamel who wanted to destroy the Smurfs (which is a strange idea, because the reason why he started to bother the Smurfs was because he needed them as ingredients for creating gold (see "Le voleur de Schtroumpfs" in the book "Les schtroumpfs noirs" (Éditions Dupuis, 1975).
In the book "La schtroumpfette", Gargamel created a small statue of a Smurf (using regular clay) and after use a spell named, "How to make a statuette with a feminine personnality". According to that fact, the smurfette is not a smurf, she is only an animated statuette, but to me, she is a -ette (in the feminine sense of it), since she has a feminine personnality. This fact bring the discussion to another level: does the fact of being a man or a woman is only determine by physical attributes?