My parents died when I was five. Before then, they’d raved constantly about how smart I was, but when my grandmother got custody I fell under her general assessment of children in general: they’re morons, try to keep them alive until 18 when they become someone else’s problem. The school system apparently contacted her several times about gifted programs but, eh, what did they know?
I was in my 30s before she acknowledged that maybe I wasn’t a complete moron. Ironically, despite her 5th-grade education, she was one of the sharpest people I knew; she just had a dim view of education.
I scored a 30 or so on the ACT, iirc. As someone else mentioned, there was no prep back then - we showed up at some big classroom and took a test; I don’t think I even double-checked my answers and I was one of the first to leave. I wanted to get into University of Kentucky, which required an 18 or 19, I think, so I was pretty casual about it.