This book explores the roles of both genetics and training in athletic success, arguing that both are equally necessary components of athletic achievement while considering such topics as race, gender, and genetic testing.We all knew a star athlete in high school. The one who made it look so easy. He was the starting quarterback and shortstop; she was the all-state point guard and high-jumper. Naturals. Or were they? The debate is as old as physical competition. Are stars like Usain Bolt, Michael Phelps, and Serena Williams genetic freaks put on Earth to dominate their respective sports? Or are they simply normal people who overcame their biological limits through sheer force of will and obsessive training? The truth is far messier than a simple dichotomy between nature and nurture. In the decade since the sequencing of the human genome, researchers have slowly begun to uncover how the relationship between biological endowments and a competitor's training environment affects athleticism. Sports scientists have gradually entered the era of modern genetic research. In this exploration of athletic success, the author, a senior writer at Sports Illustrated magazine tackles the great nature vs. nurture debate and traces how far science has come in solving this great riddle. He investigates the so-called 10,000-hour rule to uncover whether rigorous and consistent practice from a young age is the only route to athletic excellence. Along the way, he dispels many of our perceptions about why top athletes excel. He shows why some skills that we assume are innate, like the bullet-fast reactions of a baseball or cricket batter, are not, and why other characteristics that we assume are entirely voluntary, like an athlete's will to train, might in fact have important genetic components. Through on-the-ground reporting from below the equator and above the Arctic Circle, revealing conversations with leading scientists and Olympic champions, and interviews with athletes who have rare genetic mutations or physical traits, the author forces us to rethink the very nature of athleticism.