Such a strange question....
1. Well my parents are divorced, and better off that way, so I'd rather them walk in on me.
2. Even though I don't have kids, if I was to walk in on one of 'em, I think that there would be some serious ass-whooping (or at least scaring) to do on their partner (if I had a daughter), and if it was a son.... a serious, and scary talk would be in order for him, me thinks.
3. Answered above in #2