Also a lot of that’s locked in by structure. If you buy a house in an American-style suburb, your kids are going to be spending a lot of time sitting in car seats and commute times tend to cut into the time needed to cook healthier foods at home.

A kid can’t decide to move and in many cases it’s really hard to use alternatives: either neglect or deliberate attempts to discourage pedestrians mean that there’s very little in walking distance and often not even sidewalks or road crossings which don’t require substantial detours. It may or may not be safe / conducive to cycling but the safety culture is such that a lot of habits are set by the time they’re old enough to do that independently in their late teens.