Accursed are those who have been forcibly turned - accidentally or otherwise - and have less control over when and where they shift. They are emotionally volatile in that way, high emotions make them turn, and they lack control when shifted unless otherwise trained and assisted by inherents.

Inherent lycans CAN'T actually spread lycanthropy to others - it is genetic! Accursed CAN, however - origins are hard to track, but most agree it was a foolish curse made by a vengeful werewolf who wanted revenge for being hunted. It backfired, clearly, so now there's efforts to control the spread.