Maybe they don't have the knowledge, or maybe they don't know how to effectively apply it, but it seems that many are failing to make a real-world positive difference on the lives of their children.
Parenting certainly is getting more difficult with more information and access to resources available to kids, and I believe, we cannot have all the knowledge or know how effectively to apply them, but still there are some basic lifestyle habits, that must be put into practice - you enforce or encourage or do whatever, that's the responsibility we must take. Over time,they become habits and they will thank us later when they grow up - just my thoughts.
And the basics are not that hard, are they? Sure, people can have differing belief systems, but a healthy diet is simple.
And doing nothing else while eating....