Kelley, who in his youth wanted to become a doctor like his uncle, but whose family could not pay for a medical education, in part drew upon his real-life experiences in creating McCoy: a doctor's "matter-of-fact" delivery of news of Kelley's mother's terminal cancer was the "abrasive sand" Kelley used in creating McCoy's demeanor. "Star Trek" writer D. C. Fontana said that while Roddenberry created the series, Kelley essentially created McCoy; everything done with the character was done with Kelley's input.