That logic would be comforting if we didn't all disprove it....we all overcame our bad upbringings, so why couldn't our parents overcome theirs?
A lot of people our ages, who are raising kids, or just finished raising kids didn't overcome bad upbringings. People have different abilities when it comes to seeing that their own parents raised them poorly and the need to overcome the damage and not pass it on.
I don't think my mother realized her parents weren't always the best parents and that they did damage to her by berating her as difficult, impossible, lazy and dreamy. They tried to force her to be neat, tidy and efficient. Mom was a creative artist and musician type. She needed to be dreamy to create. She wasn't the immaculate housekeeper type, but we always had three square meals, clean clothes and sheets. We kids took turn doing dishes and doing chores. While you may not have been able to eat off our floors, the place looked good and we knew where things were.
One time my grandmother told me that my mother was lazy. I told her that Mom had six kids. I also listed all the things Mom did with no help from Dad. My grandmothers were fairly wealthy and they both had maids. I pointed out that mother did not have a maid and she often worked as well as giving piano lessons.
Yes, my mom did some terrible things to us kids. So did Dad, though he didn't yell at us or abuse us physically. They also did a lot right. I have learned to look at them as human beings, individuals and not just parents. They had their own pain and sorrow as children. Unfortunately, no one is guaranteed a good set of parents, good genetics or happy childhoods. Mental illness can factor in as well as poor physical health. I had some unhappiness, but I also had a lot of fun and freedom.
I want my children to be fair in their views of me. I give my parents the same consideration? It doesn't excuse the things they did to me, to realize my parents were just grown up children. It does help me to understand why they happened. Considering that my parents were very flawed and very human also helps me to heal and realize their actions were not my fault.