RPGs, Problem Players, and Parenting

So Dave over at The Concierge posted last night about a situation that he experienced at his gaming table.  Technically, it wasn't at his table, because he was playing in a game DM'ed by his highschool-aged son.  I found it to be an interesting post, and dilemma, from a number of perspectives.

I say go take a look at it, and then stop back here.  (If you decided not to, here's the gist: Dave is at the table DM'ed by his son.  Two players (his son's age) prove to be 'difficult'.  Dave reacts as a parent, perhaps instead of as a fellow player.  Interesting thoughts and a few questions ensue.)

First off, while I know many bloggers out there (here?) write about getting their children into gaming and/or DM'ing for their children and children's friends, I don't believe that I've ever come across a blogger talk about playing in his or her kid's game.  I'm sure it's happened--I just haven't encountered it.  So, in my mind, the first question becomes, how many people out there play in their kids' world?  Based on relative ages and mathematics, I'm sure that there are plenty.  What's it like?

Second, if you aren't the DM and therefore not "responsible" for play at the table, how far do you let an awkward situation go before you step in and attempt to "fix" it?  Are there ever situations where you just decide to let the DM go down with his ship?

I've some other thoughts, but my bed is calling out to me,

If you've come across this situation or similar ones, drop over there and leave a comment or two for Dave.