These are Intrinsic Keys that bond the curser and the cursed. The Curser has the key imprinted on both parties. Only way to break curse is for the Curser (or a descendent of the same bloodline) to cut the key and draw blood. This must be done with the same gouging staff used to create the curse and in the location of the original curse.
If the curse is big enough, breaking it would drain the life of the curser.
All curses are passed on through the generations unless they are broken or the cursed bloodline ends.