appropriate action...

What is the appropriate action to take when it is seen that adolescent grandchildren that you love are heading down a path to hell?
By hell i mean that they are being consumed by the illusion that what matters most in the world is that their peers think they look good. That their possessions are as good as their peers possessions. That their self worth is determined be the acceptance of their friends and the advertisements on TV. That the taste of what they eat is much more important than it's nutritional value.
Can i do anything? Should i do anything?
For any offering to be accepted, without doubt it must have no element of criticism.
Waiting for enquiry may be the most appropriate attitude....
But then i might wait forever, but as it's their trip (not mine), that's ok too.