Any sufferer knows: Carsickness runs in the family.

But is it genetic, or just the power of persuasion? When Mom turns green, is that what makes Sis queasy?

Penn State psychologist Robert M. Stern and gastroenterologist Kenneth L. Koch have studied motion sickness for many years, sitting volunteers, motionless, inside a horizon-shattering rotating drum (see R/PS September 1988). The insights gained from that nausea-inducing set-up have helped people as diverse as astronauts and mothers-to-be with morning sickness.