Parents have instill the value of learning. I was read to every night as a little kid, until mom made me start reading to myself with her oversight. I could read when I got to school.
My parents were HS educated, but better educated than most of the other kids in my college classes - they graduated in the 30s. Dad worked as a chemist before and after WW2, and by the time he retired in the mid70s, most of his coworkers had grad degrees. Standards have been dropping for decades.
Private schools. Meh. I don't care either way. They can be great; they can suck. The public schools where I grew up (upstate NY) were excellent, and far better than the Catholic schools. We would have kids come to the public schools from the local Catholic schools and they were far behind, even in junior high. I had no idea that this was a complete aberration until years later. Even in other suburbs of Rochester, it was not the experience. I remember a friend's cousins, Orthodox Jews, who went to Jesuit schools because they lived on the wrong side of the city/'burb boundary, and could not get into the Brighton (IIRC) schools in any way. That must have been as weird as can be. The Brighton schools were the only ones as good as ours; they sometimes had more students who maxed the SAT/ACT testing than we did.
I did my first two years of college at a community college when I moved with my parents to the midwest and valued it more because I met a variety of people of different backgrounds, not because of the classes in and of themselves. I transferred to the big U (UIUC) for the last two years, and was sometimes aghast at the poor prep displayed by other students. Not a lot of them, but some.
I went to a top flight law school (also UIUC) as a guaranteed admit based on grades and test scores. Hated it, did poorly. I don't think I had any classmates who were not top flight intellects, though. Now I deal with a staggeringly number of lawyers who are borderline illiterate. It's crazy making, in part because responding to a brain-dead argument is harder than responding to a well-written brief that takes an unsound position. I just had a conversation with a baby lawyer who does work that put her in opposition to me. That didn't bother me. The fact in her school Criminal Procedure was an elective boggled my mind. I know most private lawyers will purge that just as I did with some topics - but she did not even have the basic knowledge an engaged private citizen should have was amazing. And this was not a dumb baby lawyer, either - obviously well educated in general and well spoken.