I'll let Wikipedia do most of
the work for
me.
Here's some info Daniel Knauf (the series creator) provided for pre-show canon:
In 1916, Benjamin John Hakwins was born on a farm in Milfay, Oklahoma to Henry Scudder and Flora Hawkins. Scudder abandoned the family while Ben was still a baby, leaving him to the care of a 'goddamn crazy woman' (to quote Ben). After her son's birth, she began to believe that her husband was in league with the devil and that her son was the anti-christ. The mother of an Avatar will inevitably suffer trauma at his birth, most often manifesting in insanity. In no way helping her condition, Ben began to display healing powers as a child. One night, he dug up his dead cat and accidentally resurrected the creature midst adamant refusal to hand over the corpse. This miracle set a spark to Flora's religious fervor, and from that point on, she refused to touch her son, believing, with all certitude, that he was marked by the devil. For days on end, she would often subject him to vitriolic rants underlined by scripture readings.
Healing or reviving a life, animal or human, also requires a price: life for life. All the crops on their farm withered in exchange for that cat's life, sending the already struggling family into abject poverty. This would only be exacerbated by the Great Depression in 1929.
Perhaps motivated by poverty and Flora's treatment, Ben left the farm at 16 and headed to Houston, Texas, where he became involved in a life of petty theft and burglary. As a result of a failed bank robbery, Ben was convicted and given a 20-year prison-farm sentence. However, he wasn't there for long. Word from a neighbor informed him that his mother was dying, and desperate to see her, Ben managed to escape. It wasn't as easy as stated. Unable to secure a release, Ben reacted with belligerence and was placed into solitary confinement as a result. Pressed to the edge, he switched gears and found efficacy in playing dog. Ben stuck to the rules, and acted like the teacher's pet in a third grade class. Demeaning as it was, he was rewarded with an invitation to accompany a guard to the nearby town for a gravel run. Ben took the opportunity to take over the wheel, only to have the guard turn a gun on him. In desperation, he took the guard's gun and killed him.
Immediately following the murder, Ben drove the car down to Milfay. Soon, he would find himself picked up by the Carnivàle after his mother's death. In the middle of burying his mother, actually.