When familiarity doesn't have its boundaries it will definitely bring insult, like it or leave it.

Let me share my experience:

I have a relative that's living with us, much more younger than I am; even with that knowledge, I gist and play with her, I crack jokes just to make her laugh, I help her with her chores. This was to make her feel at home, even when she is not in her own home.

Recently, I notice that, if i don't help her with her chores, she will frown at me, she won't even wish me goodmorning as usual. If i call her, she will respond after 10sec. I needed no one to tell me why she was doing that, I just knew it's because I made myself simple and foo friendly to her.

Although, I can't quarrel with her, but I have withdrawn myself from her. I dont help her anymore, I dont crack jokes again, I'm just living with her, as I would have lived along time ago.

So familiarity without boundaries,truly brings insults.