Causes. The cause of TS is unknown. However, it is a condition that is genetic with environmental influences. It is known to run in families but having the gene does not mean a person will develop the condition. It is believed to happen when nerves in the brain have trouble communicating with each other. Chemicals in the brain (neurotransmitters) that pass impulses from nerve to nerve may malfunction. It is a very complex disorder, with multiple genes involved. Environmental factors are also being studied.