Parents who have unconfessed sin cannot possibly discipline their children because of guilt.
I noticed this in my family of origin.
Primarily when I was a teen my mother let me run wild because she was doing the same thing at the time (she was not doing well with middle age I guess). My high school academic career was wasted and I blew off scholarship opportunities and didn't use my talents to better myself. It took me many years to parent myself and it wasn't until I became a Catholic that I really grew up.
I find that I have moral authority and credibility with my kids because they see me going to confession and receiving the Blessed Sacrament. They cannot say I am a hypocrite and that counts for a lot with teens who have a strong sense of "fairness".