Like anything, you don't force kids to cook. It just becomes part of life - have them be around it, keep them informed - talk about it. I try to relay my passion for it in these ways. The second you try to force anything on your own kid, they rebel.
It's great that people are basically spending their two weeks of vacation to come out and be with us in some weird part of the world. And I think we owe it to them to take 'em to some cool places.