A friend of mine believes he has control over his kids lives who are in their late 20's. Furthermore, he wants control.

In reality, control is a fleeting illusion. It's like trying to wrangle a herd of cats.  While we may try to govern external circumstances, true mastery lies within. (a Buddhist joke comes to mind:)

We can't command the world because the universe throws curveballs, Murphy's Law lurks in the shadows, and chaos reigns supreme. But we can harness our reactions, choices, and mindset. 

If you want to control anything, start with yourself!