David Epstein is the author and, at times, first-person narrator of The Sports Gene. He’s a graduate of Columbia University, where he was also an award-winning track athlete. A senior writer for Sports Illustrated at the time of publishing and presently an investigative reporter for ProPublica, Epstein has written about sports science, medicine, and Olympic sports—a body of work that establishes him as an authority on the subjects he investigates in The Sports Gene. True to his background in investigative journalism, Epstein largely maintains authorial distance in the book, reporting in a journalistic style.

Epstein’s identity as a runner contributes to his authority on the subject of sports while also giving him opportunities to expose his personal connection to the material. In “The Talent of Trainability,” Epstein includes a story about his own college track-and-field experiences and a training buddy whose path differed from Epstein’s own in ways potentially explainable by genetics. He uses this story as an example of how probably-inaccurate narratives arise to explain what are most likely scientific facts: A great runner who doesn’t improve through training, like Epstein’s friend, may not be lazy (as he was described in college) but may simply be a low responder to training.