Air sickness isn't caused by banking. Motion sickness is caused by the balance system's inertial sensors (the inner ear) sending different motion information to that sent by the eyes, which confuses the body's control system. That's why you get (bad) motion sickness on the jump seat of a jetstream 31 (the one at the back of the cabin) if you look out of the only window you can see (the centre windscreen panel). Your vision and innertial sensors see things on opposite ends of the seasaw pivoted at the CG (to keep it simple). So when you get yaw-bumped left your eyes see it as bumped right, and the same with pitch-bumps.
PDR