-You need to drink the werewolf pure blood to become one(Wtf i tought that u need to be bited like in bloodmoon.)
-Hircine(deadric lord of hunts) created it.
-In the companions quest,Kadlak hints more than clear that lycanthropy is a curse saying about
Spoiler
witches cursing them , killing the werewolf spirit,hircine taking their souls from sovengarde and blah blah blah
Those things goes totaly agaisn't the Lore i know about TES.If lycanthropy is really a curse how the hell there are lycanthrope animals?