Forrest was born near the small town of Greenbow, Alabama, on June 6, 1944. His father was absent during his life, and his mother said he was "on vacation". His mother named Forrest after their ancestor Nathan Bedford Forrest, a Scotch-Irish American and a noted Confederate general in the American Civil War and the first Grand Wizard of the Ku Klux Klan. She intended his name to be a reminder that "sometimes we all do things that, well, just don't make no sense".
Forrest was born with strong legs but a crooked spine. He was forced to wear leg braces which made walking difficult and running near impossible. He also had a relatively low I.Q. of 75, which nearly prevented him from being accepted into public school. (His mother managed to get the principal to reconsider by letting him have intercourse with her.) Despite his physical and mental challenges, Forrest's mother told him not to let anyone tell him he was different, telling him "stupid is as stupid does".
Forrest and his mother lived in a large house just outside the town of Greenbow. They made money by renting out rooms to travelers. One of their guests was a young Elvis Presley. Forrest liked dancing to Elvis' music and his leg braces gave him a unique dancing style that would inspire Elvis's "hip dancing", for his song "Hound Dog".
On the bus ride on Forrest's first day of school, Forrest met Jenny Curran and was instantly taken by her. "I had never seen anything so beautiful in my life," he would later say of her, "she was like an angel." The two became close friends, often playing around a large nearby tree. Forrest described their relationship saying, "Jenny and me was like peas and carrots." Jenny was one of the few people besides his mother to accept Forrest as he was, helping him learn to read and stand up to bullies who harassed him. However, Jenny's home life was not nearly as happy as Forrest's: her mother had died when she was five and her father was an abusive alcoholic who molested his children (until Jenny was taken away to live with her grandmother), and Forrest's friendship offered her an escape.
One day, a group of bullies was throwing rocks at Forrest, and one of them cut his forehead. Jenny told Forrest to just run away, which he did, only to prompt the bullies to chase him on their bikes. As Forrest struggled to run, his leg braces broke apart. Once he was free of them, Forrest was able to run incredibly fast. Forrest would never wear leg braces again, and was able to run anywhere he wanted to after that.