What are the chances of tourette's being passed on to a child, from a parent?

Some. There is a chance of it being passed to the child especially if the child is male. On the other hand the child might not develop tourette's syndrome, but rather OCD or a milder tic disorder (or no problems at all). In other words they may have some of the other behavioral problems associated with tourette's. In some families it is inherited more strongly than in others.