I've been trying to write a book for years about a post-apocalyptic society entirely run by children, in which all of the adults died off and the children have to figure out how to survive and, eventually, rebuild. However, I cannot figure out a plausible way for all of the adults to have been killed off. Maybe by some sort of sickness? I'm not sure how I'd just kill off adults, though. Any ideas on what might plausibly kill off the entire adult population?

These people can (and must, for the story to work) grow to be older than 18. The thing can move on or still exist, it doesn't really matter as long as it doesn't kill off the remaining children in mass quantities.

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    $\begingroup$ Related (possible duplicate): worldbuilding.stackexchange.com/q/29877/627. $\endgroup$ – HDE 226868 May 9 '17 at 14:59
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    $\begingroup$ Welcome to WorldBuilding by the way! If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$ – Sec SE - clear Monica's name May 9 '17 at 15:04
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    $\begingroup$ Do you need to kill off "people who have lived more than 18 years" or do you just need to generally kill off adults. Tying the event to an arbitrary point in time like your 18th birthday is going to be much harder than just generally killing adults, with a little slop room permitted on each side. Some "children" will die, some very young "adults" will live. $\endgroup$ – Cort Ammon - Reinstate Monica May 10 '17 at 3:55
  • $\begingroup$ Should the cause for killing of everyone above 18 persist or should it be a single event klling off everyone above 18 once and then the people age normally beyond that point? $\endgroup$ – Adwaenyth May 10 '17 at 13:14
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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. If you want to discuss possible answers, works of fiction that have used this theme, or anything else that isn't specifically about improving the question, please take it there. $\endgroup$ – Monica Cellio May 10 '17 at 20:21

32 Answers 32


AI goes rogue, kills everyone using sufficiently advanced technology it just invented for the purpose.

But it cannot interfere with minors, due to a safeguard built in. One of the few it was not able to disable nor work around, at first.

While it's trying to disable or work around that safeguard, another safeguard is triggered and kills it.


What about explosive ID cards? With some handwaving, you could establish that in your world, all adults were issued one. If you have trouble coming up with an explanation for an explosive card, what about hack/malware wiping adults through an ID chip being routinely implanted at some appropriate age?

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    $\begingroup$ A society consisting solely of the young and the forgetful. $\endgroup$ – Michael May 11 '17 at 9:15

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