Bottom_rung- there's a few references to them. If memory serves, there's a moment where the PHB hires his own son to act as a subordinate, and there's a moment where he gets a call saying "WHile you were working, your children grew up and moved away." But, considering the.. thing... that created them, I wouldn't be surpised if they're adults who still play with ovens.
The only reason I remember that latter comic is because it has one of the strangely funniest moments -EVER.- The phone ringing and the boss thinking, "Ringy thingy." I've seen it on T-shirts.
@ hrimhari - If you dolly in and zoom out the camera lens will be in front of the foreground objects. As the staff on the far side of the desk are in a flat plane the perspective will not seem to change much. Anyway I was joking. Alice and Dilbert aren't in the frame so there's a clear view of Carol. Now - the real reason for this - PHB has spawn? Have they ever been in the strip?