Ratliff grew up in the small town of Demopolis, Alabama. He and his two brothers, Thaddius and Timothy, were raised by their mother, Camillia. Although his tall, skinny build was suited to schoolboy basketball, he wasn't immediately drawn to it. He tried baseball and football in junior high before he found his sport of choice:
I originally started playing baseball because my older brother was playing baseball at the time. But I was never that good at it... ... At school, we would play tackle football. And then one of the kids got hurt, and then they stopped us from playing tackle so everybody was like, "Well, I'm not playing touch ," and everybody just went to the basketball court ... I enjoyed the game so much, I just never stopped playing.
Throughout middle school and high school, Ratliff remained fairly injury-free and healthy other than the scrapes, bruises and occasional broken bones that most kids experience. He excelled at basketball, particularly on the defensive side. At Demopolis High School, Ratliff helped the team to records of 19-6 and 25-4 his junior and senior years. During his high school years, he avoided the weight room, at the time believing the common misconception that adding more muscle to his frame would mess up his shot. As an undersized high school senior who hadn't completely filled out, he was realistic about his prospects for reaching the NBA:
My whole thing was to get a free education. I watched the pros, yeah, but I didn't think I'd get to play in the NBA. Because I was a small kid. Real skinny. I was tall but I was real skinny ... I didn't care where it was, I just wanted a scholarship ... I looked at is as a ticket to not having my mother have to pay for college.