The forces of dark magic can taint a character who comes into contact with them. This can have some positive effects, such as giving the character a supernatural power, but it often has an even heavier social stigma. Nobody trusts a witch-marked character of any sort, not on the Benighted Earth.
Witchblooded- a witchblooded character has a witch ancestor. Witchblooded have a strong affinity for magic, learning and casting spells with more ease than an untainted human, but tend to be obsessed with either magical knowledge, temporal power, or both. Witchblooded characters may have a minor, almost unnoticeable sign of their taint – a strange but hidden birthmark, psychological quirks, etc. etc.
Witchborn - a witchborn character has a witch parent. Witchborn characters have an even stronger affinity for magic than witchblooded characters, but have an even stronger obsession with either magical knowledge or temporal power. A witchborn character has an obvious sign of their taint – birthmarks, deformities, odd eye color, etc. etc.
Witchmarked - witchmarked characters have been permanently affected by magic, either a spell cast on them or an ancestor, or by the taint of a place of power; this mark has changed the character, given him some weird power (player-defined), but at the same time inflicted on him some special weakness (also player defined). For example, the character is not hurt by flames, or will not be attacked by animals, etc.