Reading more into my General Psych book and it is talking about intelligence. Identical twins almost always have the same IQ levels but if they reach that genetic potential they were born with all depends on environmental factors that encourage the child of reaching it.
By the laws of science Stanley Pines has the same IQ level as Stanford but they were both treated differently in school and home life so they both developed it differently.
Stan was clearly not a book learner. If I had to peg him as anything I would say he is more hands on. He just goes for something without reading the instructions and can probably do it pretty well. Ford is the typical book learner that teachers love.
Home life was all about Ford and how great he was in school and Stan put all his might into boxing once he figured that was something he could do well and get praise for. Then comes everyone called him dumber then Ford so he never really tried to go for the high test scores because he probably (subconsciously) thought he could never get great grades.
I know it is old news that Stan is super smart like Ford but I like having the science behind it.