Here's a great piece by Jerry Cimino, founder and curator of The Beat Museum in San Francisco: Heroes and Anti-Heroes.
I can relate. Like Cimino, my parents lived through the beat generation era (Dad born in 1904, Mom in 1924) yet chose the conforming route. I guess I'm thankful for that, or I wouldn't be who I am today. Not that I'm anything special (no one is), but I guess what I'm saying is that I don't live in regret over all the things I could have been and should have done (or not done). Why? That's where I go full circle and connect to what Jack learned from his Buddhist studies about such things (e.g., nonattachment). I didn't learn about how to live without regret from Jack (and I'm not 100% there as it is and never will be), but rather from my own venture into Buddhism and related eastern thought. However, my own studies (Alan Watts, Pema Chodron, Thich Nhat Hanh, Eckhart Tolle, Jiddu Krishnamurti) sure helped me connect to Jack's writing about the topic.
Should is the most destructive word in the English language. My parents, as yours, did what they did at the time and that's that. Should they have been different? Well, that's not only a moot point (the past is the past), but it's irrelevant to your happiness today. You can wallow in what your parents did or didn't do, or you can live your life as fully and engaged and compassionately as you can, including not blaming others and events for each and every one of your behaviors. You are a thinking human being with the ability to choose in all situations.
And please quit "shoulding" on yourself and everyone else.
P.S. Sorry for the ramble. It just happened and I went with it.
P.S.S. Please understand that I am not excusing parents for bad behavior, nor am I saying that their practices have no effect on how a child turns out. Some parents do things that are evil and wrong by anyone's standards. What's really sad is when children physically survive a horrific upbringing and then needlessly suffer emotionally for the rest of their lives, especially when there's a way out of it. Some can discern the way more easily than others, but it is still there.