To my knowledge, this was a feature that never carried over to the later Fallout games, but in Fallout 1, if you gave your character an intelligence of 1, it would come out totally stupid! Even the NPCs get annoyed with your grunting and unintelligible dialect. I think the only real consequences of a low IQ in today’s RPG characters is the inability to open chests or hack computers – I want them to bring back the character path where your guy is a complete moron!