Note: I struggled with deciding which Stackexchange site to post this question to--Law, World Building, Scifi, or Parenting--but hopefully it fits well enough here. I know it's not a perfect fit, but I hope users here will know more about the government and legal side of this question.
Also note, this is hypothetical, but I really am curious about the real-world ramifications.
Yesterday I watched "Miss Peregrine's Home for Peculiar Children" and at the end of the movie the main character, a teenage boy,
leaves his parents to join the "magic" society that he has become a part of. Presumably never to be seen again by his parents.
Something similar happens in other fantasy novels, but I can't remember them right now.
My question is this: If, in real life, a child of a family were to suddenly disappear, what legal or social ramifications would the parents have to deal with?
Would the parents have to fake the kids death?
Would the parents have to convince the school district that the kid is somewhere else or home-schooled?
Would they have to lie to the IRS?
I assume they'd have to have a good excuse for family, friends, and neighbors, but how foolproof would their excuse have to be? What if after 5 years, the neighbors get suspicious of the missing child and the police get involved?
Basically, I am curious if a kid could just disappear off the face of the earth without arousing suspicion from the government. (Even a few decades later--"We have records of your kid going to elementary school 10 years ago, but no death certificate, where is your kid, ma'am?"). And, if suspicion was aroused by neighbors, what would happen?
Let's assume the family lives in an urban area in the US.