In a messed-up world like Fallout, it's not surprising that some people would turn to cannibalism. Still, cannibals make for some of the more disturbing characters in the game.
Here's a look back by ShoddyCast at the many (!) factions and people in Fallout 3 and New Vegas that eat other humans. I remember being unsettled by the assholes from Andale, but arguably they had an excuse—it's hard to survive in the wasteland. The White Glove Socity, on the other hand, were the worst. They had money and could eat anything they wanted! I didn't feel bad wrecking them all.
FALLOUT Lore: Volume 6 - Cannibalism [ShoddyCast]