They watch you make mistakes, they tell you when they think you should do things differently, they stand by you when you can't stop making those mistakes and they help you when you need it.
I find it baffling that people who have appeared to be strangers for years can provide such a strong support system. Even when you don't realize or want to admit to yourself that you need help or that there even is a problem, they are there for you. I guess that's what I always wished for my family to be like and now it is.