Corrine and Olivia (Flowers in the Attic, by V.C. Andrews)Read about the other entries on the list.
The brilliant trick of V.C. Andrews’ novel about incest, greed, and spectacularly bad parenting is that it initially presents Olivia, the grandmother, as the true Monstrous Mother, and Corrine, the mother, as a goodhearted parent who is guilty of incredibly poor decision-making but not true evil…then it slowly turns the tables, not by making the grandmother a better person but by making Corrine the worst person. Poisoning your children slowly (while forcing them to hide in the attic) in order to assure your inheritance is actually more horrible than locking them in closets for days on end. At least Carrie got to attend gym class from time to time.
Flowers in the Attic is among Jeff Somers's top five books featuring runaway parents and Nicole Dieker's top nine books even non-readers will love.