That sounds a little more rational to me.Because I think that you can't put exeptions in spells.Like this spell turns who ever steals this cookie into a toad,unless it's a girl and is cute.I don't think spells recognize one person's particular feature to distinguish them from another and choose for it'self whom it curses or not.But diferent races and their effects on or by magic is more plausible.Like Hagrid taking all those stunig curses from the Auros in book 5,because his half giant and they are inmune to some magic.Oii,I think I wen't to deep with this but thanks for the info guys!!!!