It's still a mystery to me why that connection was never made.

I feel the same as you, but as I am nearing 30 myself now, I think I have figured out some things that may have escaped me when I was younger.

There was the typical stuff, like how my mom tended towards being too overprotective while my dad was simply too aloof. He also had some anger issues and occasionally would get violent on my mother until I was old enough to stop it. Like all kids, my parents didn't seem human, but for me, this never changed.

From middle school onwards, they were focused on their own problems that they had between them and completely stopped paying attention to my development and progress. Most days I came home to an empty house and fed/clothed myself. Because I was an only child, the lack of motivation and lack of companionship made me into a shut-in video gamer and still haunts me to this day in the form of social anxiety. These were hellish times for me and I developed an oversensitivity to conflict. I couldn't sleep at night sometimes because I was intently listening to hear if they were fighting in their room.

This culminated in a divorce during HS and a big conflict where I had to threaten suicide to make them stop fighting. This was the only time I legitimately considered suicide as I had been dumped by my GF and in the same week, had paranoid suspicions that my dad had finally killed my mom to avoid the divorce case.

I have ZERO idea of what my parents were like as adolescents and frankly, I don't think it will change how I think of them. They were much too embroiled in their own problems to track the development of the little human they created by accident. Instead of being my role models, they gave me examples of what I didn't want to be when I grew up. Because of this, I grew up having no idea what I really wanted but knowing exactly what it was that I DIDN'T want.

Final story: During my final year of HS, my dad sees me with a cigarette for the first time and starts the typical dad rant. Maybe he wanted to be more dad-ish since I'd be going off to college. By then, I had already been smoking for 2 years. When I told him, that shut him up.