Good point about children and fanaticism. We have the recent exemple with The Killing Fields. Some psychiatrist on tv said kids are basically sociopaths and that only through growth and good role models do they change and feel empathy. Give a kid a gun and tell him to kill adults is jolly good fun. Until they hit 21 (30 in the movie) when "their palm flower crystal embedded in the palm of their right hand" makes a last color change to black. Oopsie!
There is an argument that Hitler took mass murder and turned it into a manufacturing process, and I think that's true. But under Lenin and, more importantly, Stalin, the gulag, though more spread out, was just as much a killing machine using the young to grind the gears of The Great Purges. Only to be replaced by a later group of youngsters. And so on. When you're young and marching toward Utopia, you're invincible, until you aren't.