Why is it that when your parents are yelling at you for something and talk back at you, it's acceptable, but when a son or daughter does the same thing they end up grounded or get kicked out?

My family has been hanging by each others throats the last couple of days. I'm an only child so it's hard at times trying to get my points across when I have two other people going at me. Just now I tried explaining my point of view in the situation to my mother and it ended up with her locking herself in the bedroom balling her eyes out...

What's Reddits take on a similar situation?