He is also quite strong and agile, despite his size, and can easily defend himself in a fight.
In his early life, he lived in a trailer near a construction site Charles Kramer owned along with his twin brother John Sheppard and Ann Sheppard. One day, the two brothers are kicked out of the trailer by their father who is drunk. The twins then decide to go and play at the construction site. After a while, the twins play hide-and-go-seek, and John Sheppard decides to hide. To Scott's horror, he finds his twin brother caught in an open pipe gradually filling up with water. He attempts to pull him out, but fails doing so. Scott runs back to the trailer for a plea of help to his father. His father then goes onto say if John dies, it will be 'one less mouth to feed'. John Sheppard dies of drowning and pleas with Scott to never forget him. Scott is later adopted by the Shelby family.
Scott Shelby is the true identity of the Origami Killer, the game's main antagonist.