It's an important lesson, because teens (well, all of us, really) are exceptionally skilled--often completely unconciously--at how to foster domestic disharmony. They/we know how to push family members' buttons. They know what kinds of behaviors will annoy siblings, what will drive parents crazy, and what to procrastinate on for maximum panic and chaos at the last minute. So it's useful to remind young women that there's a certain amount that's under their own control, especially when it comes to their own responses, and to nudge them to be more aware of how their own actions, instinctive responses, or knee-jerk behaviors might be contributing to the family atmosphere.