In Fallout 3, most children (not adolescents/teens) are made unkillable in the game. Aside from modding the game or artificially ageing them with the console, which can you kill anyway?
I know of two in the main game:
You can kill Harden Simms and Maggie - they both die when you nuke Megaton.
Are there any others? What about the DLCs/expansions?