The GURPS psionics system.
There are restrictions:
Sorcery is the divine sanction of feudalism by hereditary bloodright. The sorcerous character must be at least Status 2, or bear the social stigma of being a bastard.
The character may possess one power only, determained by what power his father possessed. A character cannot have (for instance) ESP from his father and Telekinesis from his mother.
The king has the authority to revoke the divine sanction and strip a sorcerer of his powers.