Related Clues:

• Involuntary twitch
• It may be dominant or recessive
• Recurrent twitch
• Feature
• Peculiar situation
• Eccentricity
• Part of one's inheritance
• Distinguishing attribute
• An X could represent it
• Little jerk
• Three-legged calf, for one
• Involuntary muscular contraction
• Game opener?
• Freak
• It's not the norm