Because grandson was brought up a vegan he's been used to arguments against some foods from the start, although dad is not even veggie. He decided recently to be veggie and eat dairy things and has eaten eggs for a year or so. His mum had said when he was old enough to understand and decide he could. He's 9. He's been in Woodcraft, school gardening club and been taken foraging and on camping done that too, so does know where some foods come from. You'd expect the child of a Greenpeace employee to be brought up like that :). It did make it easy to refuse things like cakes or chips from chain food places for years, but that's no longer true :)