In addition to the Shadow Children sequence, Haddix has written more than 40 books for young readers of all ages. The series is known as the Shadow Children sequence. While Among the Hidden was initially intended to be a standalone novel, Haddix eventually wrote six more books that take place in the same world, some of which feature Luke. Though Malthusianism as it was originally proposed is sometimes considered overly pessimistic today (particularly because the idea was proposed before the Industrial Revolution and before advances in farming technology), overpopulation was still a concern into the 20th century and still concerns many today. Proposed by economist Thomas Robert Malthus in 1798, a Malthusian catastrophe is what would happen if the world’s population increased too fast for food production to keep up, and there wasn’t enough food to support the people on Earth.

While it’s worth noting that the novel’s protagonist, Luke, never figures out the truth about exactly why his government instituted a two-child policy, his friend Jen shares that they instituted the policy to avoid what’s known as a Malthusian catastrophe. Known as heihaizi or “black children,” those children can’t access public services and don’t legally exist. While some parents of illegal second children placed their children for adoption, had their children taken from them, or paid the government’s fines, others simply didn’t register to get their children government ID documents. The government also forcibly sterilized people, mostly women, and mandated contraceptive use once couples had the maximum number of children allowed.

The policy was enforced sporadically, though, and some people were able to apply for exceptions to have a second child. While the policy was in place from 1980 to 2015, the Chinese government levied huge fines on families who had more than one child. China’s one-child policy is perhaps the best-known attempt to curb population growth in the name of improving a country’s economy, and it inspired Haddix to write Among the Hidden.

Among the hidden by margaret peterson