I'm surprised no one mentioned that you can kill children in Fallout 2, usually in gruesome manners such as melting them with a plasma rifle, turning them into a skeleton with a laser rifle, or just blasting them to pieces with a twelve gauge. And you were sometimes compelled to kill these children, too: If you weren't careful, the orphans would pickpocket you and steal quest items from you.
And even at the time it was controversial enough the game couldn't be released in some countries until the kids were taken out (famously rendering some quests broken).