My freshman year in college my idiot football player roommate came into the room when I was trying to take a nap in the afternoon. I was still awake but I pretended to be asleep. I heard him whisper my name but I didn't say anything because I wanted to fall asleep. He then proceeded to get naked, pop his headphones in and watch porn and go to town. Then when he finished and leaves again, he fucking leaves the video running without the headphones plugged in. Thank God I eventually fell asleep shortly after.
I've had too many weird experiences with roommates watching porn and that was enough, I couldn't even imagine another family member...