Little is known about David Moreau's early childhood. He became a scientist and a patriot who wanted to strengthen his nation of Genosha. Sugar Man offered him an opportunity to do so: The Sugar Man had come from an alternate timeline, known as the Age of Apocalypse and had obtained technology invented by his reality's Mister Sinister. Using this technology, David Moreau created the mutate-process: all inhabitants of Genosha were tested at their 13th birthday for any presence of the X-factor gene. If they tested positive, they were turned into mutates: their memories were erased and their personality changed to become completely obedient, they were sealed in special suits and their powers were genetically changed to serve the needs of their country. At this time, Moreau became known as the Genegineer (a portmanteau of "Genetic Engineer").
Dr. Moreau was even willing to turn his son's girlfriend, Jenny, into a mutate when she tested positive. Phillip fled the country with Jennifer and would oppose Genosha's policies from abroad. The Genoshan enforcers known as the Magistrates and the privileged mutants known as the Press Gang were sent after them. They captured Jennifer and her friend Madelyne Pryor, not knowing that Madelyne's friends were the X-Men. Moreau turned Jennifer into a mutate, altering her latent mutant power of cellular manipulation, and investigated Madelyne, who turned out to be not quite human, but not a mutant either. Madelyne's latent powers killed all the Magistrates investigating her and mentally attacked a representation of David Moreau himself. Shortly afterward, Madelyne and Jennifer were saved by the X-Men and Phillip Moreau and they left Genosha. This was only the beginning of many conflicts between the X-Men and the Genoshan government, who felt that they also had jurisdiction outside Genosha's borders.
In their war with the X-Men and their allies, the Genoshans allied themselves with Cameron Hodge and his RIGHT organization, an anti-mutant hate group. The insane Hodge kidnapped Storm and several New Mutants and wanted Moreau to help him absorb the techno-organic virus from the New Mutant Warlock so he could change his monstrous cybernetic form into a more human form. Moreau despised Hodge, who wanted Genosha to conquer the world and wipe out all mutants, while Moreau only was interested in Genosha's safety. Moreau assisted the X-Men in defeating Hodge, but he was killed himself by Hodge who broke his neck.
Dr. Sasha Ryan would take his place as Genegineer, but by then the Genoshan government had been overthrown and the practice of turning mutants into mutates abolished.