Here's my take. If you were shooting hoops or playing softball, would you let them play? D&D should be no different. Also, I refuse to change my game table habits for ANYONE. If I cuss at the table, I'm not gonna change just because there's a woman (or child) present. It won't be the first time they've heard the f word (or last). I think if it was anything besides a roleplaying game, I wouldn't be reading this thread. If their parents are okay with it, let 'em play. If she gets offended because you have a beer in front of her kids, or let fly with a few terms only sailors should be familiar with, she's free to stop them from playing. I'm not saying you should let them drink, or start cussing up a storm, just that if you change your habits just to accommodate kids, your game will take a hit.