The car hunger gene

I have noticed an interesting phenomenon when it comes to driving with the family (we have done quite a bit of this of late). As soon as any member of the family gets into the car, they get hungry. Now it matters not if they have stuffed themselves a half hour before, someone is always hungry. This usually happens as soon as we hit the open road, once we have left the hotel/holiday home. What is strange is that it's never all of them together, usually only one at a time. Usually only one is hungry while the others feel sick, or nauseous or need to pee, but that's another whole blogpost in itself.