Homer has a low IQ of 55, which has variously been attributed to the hereditary "Simpson Gene" (which eventually causes every male member of the family to become incredibly stupid), his alcohol problem, exposure to radioactive waste, repetitive cranial trauma, and a crayon lodged in the frontal lobe of his brain.
Homer har en IQ på kun 55, som af forskellige er blevet tilskrevet det arvelige "Simpson-gen" (som i sidste ende forårsager, at alle mandlige medlemmer af familien bliver utroligt dumme), hans alkohol problem, udsættelse for radioaktiv stråling, repetitive kranielæsioner og en farveblyant boret ind i frontallappen i hans hjerne.