After the death of Gwen Stacy at the hands of the symbiote monster known as Carnage, Dr. Ben Reilly stole a sample of the Carnage symbiote from Dr. Curt Conners' lab after he was arrested for its creation. At the behest of CIA agent Henry Gyrich, Dr. Reilly and Dr. Otto Octavius began experimenting with creating super soldier clones -- particularly of Spider-Man. In what was labelled the "Stacy Experiment," they infused the sample of the Carnage symbiote with a sample of Gwen Stacy's DNA and managed to create a genetic duplicate of her possessing all of the original's memories up to and including her death. Unable to control her symbiote, the clone of Gwen panicked and escaped custody alongside the other clones, making her way to the Parkers' doorstep.
