Andrée Marion, a 47-year-old accountant from St. Sauveur, Quebec, has mirror movements-involuntary motions on one side of her body that mirror voluntary ones on the other. When she does things that require fine movements, like brushing her hair, reaching for change in her pocket or holding her coffee with her right hand, her left hand strokes, dips or grips in synchrony. She can't help it; it just happens. It also happens to her 19-year-old son. In fact, of Marion's 23 blood relatives spanning four generations, about half have mirror movements. It turns out they also have a rare gene defect, giving scientists new insight into how our bodies are wired.
Read the full story here: Rare Mutation That Causes Mirror Movements Reflects Nervous System's Complexity: Scientific American