Peterson was born in Harlem and bounced back-and-forth between Brooklyn and Los Angeles in his early years. His father was a high school mathematics teacher, and before becoming a paralegal, his mother was an actress who performed at the Colony Theatre in Echo Park, California. Peterson enjoyed his younger days there so much that he returned to perform there after he left high school. For 10 years, Peterson studied a variety of acting methods, appeared in local equity-waiver theater and worked part-time jobs to support himself. "I just kept plugging away," he recalls.