Honestly the more I think about it, the odder my dad really was. I recall when I was a child he mentioned building houses and having to do the "trigger nomertry" to make sure it didn't implode on itself. I remember watching him do it, too. But I also recall him trying to read like a paragraph or two from novels to help me with my homework and he just couldn't. Novels for children. Then in the mid 1990s he bought a computer with a modem, for Internet access, well before anybody else in my extended family except my uncle. He took a remedial reading course provided by his church just so he could read the instruction manual to actually use the damn thing.
I think his natural intelligence was more than people wanted to admit, and he just didn't get none o' that schoolin' because he was a hillbilly survivalist from Appalachia. Kind of tragic in hindsight.