Brain-Child's parents were exposed to excessive amounts of radiation before they had their son. He was born exceptionally healthy. Before a year passed, he had learned to read. By the age of four, Brain-Child had created a true universal solvent. His intelligence came with a price, though. His skull was large and misshapen, to accommodate his very large brain. He was socially reviled, which made him very bitter. By the age of ten, Brain-Child attempted to destroy the world but was foiled by the combined might of the Avengers and the Squadron Supreme. After he was defeated, Dr. Spectrum took away Brain-Child's intelligence, turning him into a normal-looking child.

Brain-Child is from Earth-712, the planet of the Squadron Supreme.