Perhaps it is helpful to think of yourself as a new person every day. Your parent is you from yesterday, and your child is you tomorrow. Just because you had a certain opinion yesterday, doesn't mean you have to have it today. Sure, it can form the base of what you think... but you are free to change your mind. No need to excessively defend your Mom and Dad, even if you love them. And tomorrow's kiddies, well there you have to balance your needs for today and how you can give them a hand tomorrow.
I think this kind of mindset would help you to be less defensive of your current beliefs, and more keen to find out the truth. The one real problem is how to stop your kids from doing things that you know are bad for them. But kids will be kids. How do you 'sabotage' your future self by doing something that prevents them from doing something in the future... or do you trust them to make the right choices?