Upbeat film throws light on neglected disability

John Davidson (Robert Aramayo) doesn’t only swear in I Swear (12A). He also spits, twitches, hits people, breaks things and spouts racist and sexist slogans. And yet he’s one of the gentlest people you could meet. What’s going on? It’s Tourette’s Syndrome, a condition people were almost totally ignorant about when John first started experiencing…