Parents don't get a manual when they become parents (though the bible is probably the best one around). they get a child. And being human, they make mistakes. But good parents do their best to raise their kids a little better than they were themselves raised. They do their best to love and protect their kids and guide them into adulthood. It has to be one of the most, if not the most, important and difficult tasks on the planet.
My parents and in-laws all did their best to raise me and my husband. They made lots of mistakes, and we learned from them, and are now raising our own kids...and making our own mistakes. And our kids are watching, probably taking mental notes, about how they will one day raise their kids. And they will probably try to avoid the mistakes we are making. But just like us, they will discover that parents, while making mistakes, love their children with everything in themselves, and all they do for their kids, they do out of love and care for them. Even when it goes bad.
Our parents don't have to agree with our parenting style, and their parents didn't have to agree with their parenting style. I suspect we will not agree with all our childrens' parenting styles. But such is life. All we can do is respect them as they make their choices and their decisions, and love them. And be there for them. No matter what happens to your relationship, parents will almost always be there for their kids when they need them. It is what we do.
Unless your parents were really horrible, and some really are horrible, I bet you learned some good stuff from them and became who you are today in large part because of them. And for that you owe them respect for their hard work and sacrifice. (If parenting isn't a huge sacrifice, you might not be doing it right...) And as they age, they will need you, just as you needed them when you were young.
I became who I am due to many things I witnessed from my parents. My dad showed how to work hard to provide for a family. He always cared about our well being. My mom stayed home and was involved in all we did. She took us where we needed to go. We had grandparent visits, vacations, family meals each evening, time with friends, and daily life. They helped with homework and supported our interests. We were clothed, fed and taught. We were always supervised and taught to be moral. I learned about cooking, sewing, money management, gardening, cleaning, relationships, responsibility and other things because of them.
When i grew up, all i wanted to truly be was a mother of many kids...not a career woman.
So now I get to make my mistakes, though, like my parents, I am daily trying to do what is best for my family. I think i get a lot of it right. But I also get a lot of it wrong, because I am just human, and like almost all parents, I took on the hardest job in the world because i love kids and I want to make a difference in the future of society. I want to lead my kids to choose Christ. I love them more than my own life and always will.
May God bless all you parents and grandparents for all the hard work you put into raising those kids. Though you will make mistakes, you are still making the best impact on the world by loving your kids and raising them to the best of your ability.