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 arseholes from Andale, but arguably they had an excuse -- it's hard to survive in the wasteland. The White Glove Society, 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]