Sherry Birkin was born around 1986 to Umbrella Corporation top scientist William Birkin, and his assistant and new wife, Annette. Due to their key participation of developing biological weapons for Umbrella, William and Annette's work schedules were very intense and busy, and as such weren't around as Sherry grew up. Nevertheless, she loved her parents very much and enjoyed spending whatever time she had with them, with her parents feeling the same way. In 1995, William and Annette were transferred from the Arklay Laboratory to a newly-constructed underground laboratory in the outskirts of Raccoon City to finish William's work on a new biological weapon called the G-Virus.Finished in mid-1998, William refused to hand the virus over to Umbrella, instead preferring to hand the virus over to the U.S. Government in exchange for a larger reward. As such, a special forces unit was sent in to forcefully retrieve the G-virus, which was done after fatally injuring William in a hailstorm of bullets. Knowing he was about to die, William injected himself with the G-virus, turning into a hideous monstrosity, hunting down and killing or crippling all but one of his assailants. As he did so, several vials containing the Tyrant virus; kept in a sample case stolen by the Umbrella soldiers, were scattered on the ground and broke. Rats interacting with and consuming the liquids proceeded to carry the infection to the rest of the city. Sherry remained unaware of this; especially the fact that Raccoon City was to be totally consumed with zombies in a matter of days. Annette contacted her daughter at her school; East Raccoon Elementary, and implored her to head home immediately.Upon reaching their house, Annette asked Sherry to retrieve her locket from a jewelry box and quickly seek refuge in the Raccoon City Police Department, warning her not to speak to anyone. Unfortunately for Sherry, by this time the police station too had been overrun and most of its personnel were now undead. Sherry complied with her mothers request and made her way to the station, unaware of this latest development, and remained in hiding, seeking sanctuary from the zombies, Umbrella's escaped B.O.W.s, and later her mutated father. Soon, Sherry encountered another survivor; Claire Redfield (while searching for her missing brother Chris Redfield). With Sherry gaining Claire's protection and friendship, the two worked together to escape the infested precinct. As Sherry and Claire looked for a way out of the city, they were continuously stalked by the mutated Birkin. While inside the sewers, Sherry and Claire were separated. While exploring the sewers, she was able to slip by the monsters through a series of shafts and eventually found a Wolf Medal. However, what she had not realized was that the floor she had been standing on was used to dispose of trash, and was thus, collapsible. With her added weight the floor drop opened causing Sherry to fall deeper into the sewers depths. Although filled-up bags of trash broke her fall, the shock of the impact as well as the position she fell still knocked her out. Unconscious, she was unable to protect herself against her mutated father and was implanted with a G-embryo.