Mmm, doughnuts...
The Simpsons Are Actually Geniuses[]
This theory states that all the members of the Simpsons family are actually geniuses in hiding. The theory goes on to state that Abraham Simpson, despite appearing to be a senile old man, was actually a rather intelligent soldier during WWII. He was shown as being a capable air pilot, and he's also shown as being an accomplished pianist. Marge was originally depicted as being a very excellent student at school, but she chose to become a housewife and work at home because that was what made her happy. This is important, because every member of the Simpsons family, excluding Lisa, had chosen being happy over being smart.
Homer, despite being the town fool, was actually shown in an early episode of the series as being an above average intelligent man. The main idea of the episode revolved around the idea of Homer having a crayon lodged into his skull, and once that crayon was removed, he immediately became a very intelligent individual. The only problem with his new found intelligence was that it was costing him his friendship with his peers. In desperation, Homer chose to have the crayon lodged back into his skull and to become the town fool again, because, at least, he was happy.
Bart apparently picked up on this idea from observing his father. In an early episode of the series, it was revealed that when Bart was originally beginning school, he had exceptionally high grades. However, as time went on, his grades slowly dwindled, and he soon became the trouble-maker like he is now. Abraham Simpson tried to explain this to Lisa by passing it off as the "Simpson gene." However, Homer's experience with having the crayon lodged in his brain proves his theory as being wrong. It's also shown that, despite Bart's academic failure, he is an extremely good prankster. His pranks would require serious planning and calculating in order for them to work, and he uses these pranks to make him happy, again emphasizing the idea of happiness over intelligence.
Lisa is the only Simpsons family member that had decided to be smart over being happy. While she is a straight A student and an accomplished saxophone player, she is also easily one of the most depressed characters to have ever come from the Simpsons. Because of her choosing to be smart over being happy, she will never be truly happy, and will only be there to stick out as a sore thumb to her other family members.
Maggie has been shown as being able to think logically several times throughout the show's run. For example, in one episode, she saved her father's life by pulling a rifle on a mobster gang, and she was also revealed to have shot Mr. Burns in the infamous two-part episode "Who Shot Mr. Burns?" However, because she is still just a baby, it remains to be seen if she'll choose happiness over intelligence or if she'll become like her sister, Lisa, and choose intelligence over happiness.
Evidence Against This Theory[]
According to the episode in which the "Simpson Gene" is introduced, the disorder only affected those with a Y-chromosome, and has different effects on several of the Simpson men. It could be that Bart had only started to fall back on his grades because he was slowly succumbing to this hereditary disease. As for Homer being a genius, it's actually shown that his brain only bumped up to around 105, which is actually considered average.
The Characters From The Simpsons Suffer From Hepatitis[]
Have you ever wondered why The Simpsons characters are yellow, I have a theory. Every character suffers from hepatitis, which resulted them into dying, some died because of their condition, but others committed suicide because of their hard, pitiful lives with hepatitis, Homer tried to commit suicide too, but instead, he ended up giving himself brain damage, he also developed schizophrenia and hallucinated a world full of yellow people, this explains why Homer is so stupid, he originally wasn't so stupid, but after this he got brain damage and became stupid.
This explains why Homers children aren't stupid at all, while Homer is quite stupid, when a parent is stupid, that may cause his or her children to be stupid too, but his kids don't seem to have any intellectual problems at all, this is because they originally were all normal people, but later his kids and other characters died, and before they died they were still normal, so that is how they will always appear in Homer's hallucinations, however, Homer didn't die instead he got brain damage.
This also explains why Springfield has never been mentioned which state it's in or where it is, Homer did hallucinate it, but didn't hallucinate too much about it.