The Mystery of Little Lamplight

 Those of us who have played Fallout 3 are famaliar with the story of Little Lamplight. A grade school class was visiting the Lamplight Caverns, just outside DC, when the bombs fell. The caves were deep underground, which kept the children safe.  Fast forward a couple of hundred years and the caverns are still populated with only children: once a child turns sixteen he, or she, is exiled to Big Town. Where are these children coming from? Are these kids procreating in the caves? They're far too distrustful of strangers to recruit. I bet that little shit MacCready knows, but he ain't talking. Dirty, little shits.

https://www.youtube.com/watch?v=mSFA3AyA3VA