Probably more than anything else in the world. I wouldn't be close to where I am, or who I am, without mine, and that's an observation that I can extend to pretty much everyone I know well.
I am pretty sure I would be a different person, perhaps even better, but my character, as I understand it, has been shaped by my parents. Part of that comes from them staying out of my way when it came to certain decisions that would impact the rest of my life (in India parents can get very pushy about going into certain field) and allowing us to have our disagreements (and we have many).
I don't need to argue for my observations. I experienced them and quite enjoyed growing up with them.
You don't need to argue, but if you want to find the truth of the matter, then it might help to argue. Through arguing, but not through asserting, we can sometimes learn that we have mistaken ideas and change our minds.
Don't disagree there, but you cannot explain evening spent talking, Sunday mornings watching birds, Friday evenings in the library, walks explaining why leaves are green and the beauty of mathematics. In other words, how do you distill 20 years into an argument, when no one else was there to experience a second of it? I can't.
You've now described your experiences. I'm perfectly willing to accept that it seems to you that that's what happened. But did it happen that way?
Once upon a time I talked to this guy, and he runs a group of Objectivists, and says he's a huge fan of Ayn Rand, and how much her books influenced him. And he talked a bit about his life. And you know what? He had lived it roughly in the opposite way to what one of Rand's heros would have done. He played it safe, didn't stand up for his values, settled for less, cared what others thought of him, didn't have the drive to pursue difficult goals, etc
He thought he was strongly influenced by something, and lived his life by it, and he'd failed to notice how little he acted on that influence.
Such stories are common. I have no idea if your interpretation of what influenced you is correct or not, but I do know that people often are mistaken about these things.
Suppose you were genetically programmed, and part of that programming made you think your parents were important. Couldn't that account for your experiences too? (I think it could not, but only due to some philosophical arguments. I think your experiences don't contradict the genetic theory.)
Can you extend that observation to the adopted kids you know? The adopted children I know are far less like their parents than the biological children I know. Granted, the adopted children I know were not implanted in their adopted mothers' wombs, so it's not a perfect comparison, but I definitely think it's worth thinking about. Observation about parents and children who are biologically related doesn't seem to me to be particularly informative when thinking about nature and nurture.