I feel like you definitely have a point. But my experience seems to differ slightly. When I was still using facebook, my teenage friends didn's seem to care that family members were on their friends list. They seemed to post crude, sexual, offenseive things like their family members were not able to observe the posts. I think that they still posted statuses such as that because they were behind the safety of their computers or phones, and not face to face with said family members at the time.