Those kinds of long-term risks to health aren't as intuitive to a parent's protective instinct as immediate things like physical danger to a child. I think most parents would jump into action to protect their child in a moment of crisis, but our brains haven't really evolved to fear things like heart disease. Not only is that a more recent concern in terms of human history, but it's probably likely to kill you only after your child has grown to a point of relative self-sufficience.