Your stepbrother sounds like a candidate for one of those "JayWalking" episodes, where we learn that Abraham Lincoln was the President during WW-II, and that George Washington fought the Civil War, and that Canada is one of the States in the USA...
I blame the 1960s and all the "new ideas" about education that have about ruint the US. New math, and non-phonetic methods of teaching reading are major culprits, while history taught by date-memorization is so mind-numbingly boring that it's not surprising that nobody remembers any of it!
I mean, President Andrew Jackson, who married another man's wife, and threatened to INVADE a state that was threatening to secede, is interesting stuff! Ditto for Jefferson's duel with Aaron Burr, after which dueling was no longer acceptable practice in the USA. History is interesting stuff, and you have to work HARD to make it as uninteresting as modern History and Social Studies classes had made it in the 1970s. I hear it's even worse now.
Of course, I never learned reading from school, or I'd still be ignorant of History, since learning reading was made even more boring, and overly complicated than History. How dare we subject our poor children to reading Faulkner's "The Bear", just because some hoity-toity snob somewhere declared him to be a "Great Writer". My love of Science Fiction did more for my reading comprehension than all my years of School combined.
As for math, I have to use a calculator for math problems my Mom can work out in her head before I'm done tapping keys. This is because I'm crippled by the "new math" way of doing problems, while Mom learned way back, how to break problems apart sensibly (such as 12*28 = 12*30-12*2 = 360-10*2-2*2 = 360-20-4 = 336) and not forcing the problem into some sort of "multiply by 100s, then 10s, then 1s, adding zeros appropriately, then adding them up" method.