The Sports Gene

The Sports Gene Plot Summary

Introduction

The crowd fell silent as Jennie Finch, the Olympic softball pitcher, stepped onto the mound to face Albert Pujols, arguably baseball's greatest hitter. What happened next defied expectations - pitch after pitch sailed past Pujols' bat as he swung helplessly. The man who could hit 95-mph fastballs with remarkable consistency couldn't connect with Finch's 68-mph underhand deliveries. When asked later why he struggled, Pujols simply shook his head: "I don't want to experience that again." This wasn't about raw reaction time - tests showed Pujols had merely average reflexes compared to college students. The difference lay in perceptual expertise. Baseball hitters develop specialized neural pathways to predict where a baseball will go based on subtle pitcher cues, but these skills didn't transfer to softball's unfamiliar motion. This fascinating encounter reveals the central question at the heart of athletic performance: what truly determines extraordinary ability? For decades, we've debated whether champions are born or made, whether genetic gifts or 10,000 hours of deliberate practice matters more. The truth, as we'll discover, is far more nuanced and fascinating than either extreme position suggests. Through compelling stories of athletes with rare genetic mutations, identical twins raised apart, and late bloomers who defied conventional wisdom, we'll explore how our bodies respond differently to identical training, why certain populations excel at specific sports, and how understanding our genetic makeup might help each of us find our optimal path to performance. The journey reveals not just how champions are created, but how each of us might better understand our own unique potential.

Chapter 1: The 10,000 Hour Myth: Natural Talent vs. Deliberate Practice

Dennis Rodman was just an insecure little boy in the Oak Cliff housing projects of Dallas. Every night before falling asleep, he would think: "There's something big out there waiting for Dennis Rodman." Little did he know that the "something big" would be himself. Back then, Rodman's sisters were the basketball stars. Both would become college All-Americans, while Dennis, the family runt, was short and awkward. He warmed the bench for a half season of high school basketball and then quit. He was 5'9" when he graduated, enduring taunts from friends when he tagged along with his bigger, younger, more athletic sisters. After high school, Rodman worked sweeping floors at Dallas/Fort Worth International Airport. But something remarkable was happening - he was growing like kelp. By the time he was working part-time scrubbing cars at an Oldsmobile dealership, he had topped out at 6'8". When he started playing basketball again, he found he was suddenly less gawky despite being taller. In his words: "It was like I had a new body that knew how to do all this stuff the old one didn't." A family friend convinced Rodman to try out for a local community college team. He later took a basketball scholarship to Southeastern Oklahoma State, dominating for three years with averages of 25.7 points and 15.7 rebounds per game. Drafted into the NBA, Rodman went on to win five championships, was twice named Defensive Player of the Year, and became the greatest rebounder in NBA history. In 2011, the man who played hardly any organized basketball before age twenty-one was inducted into the Basketball Hall of Fame. Rodman's story challenges the popular "10,000 hour rule" that suggests expertise requires 10,000 hours of deliberate practice. While practice is certainly important for skill development, Rodman's late-blooming talent reveals that innate factors - in his case, a dramatic growth spurt - can dramatically alter athletic potential. Some individuals, despite thousands of hours of practice, never achieve elite status, while others like Rodman can rise to the pinnacle with relatively little formal training. The science behind expertise acquisition shows enormous variation in how much practice different individuals need to reach mastery. In studies of chess players, some reached master level with just 3,000 hours of practice while others required 23,000 hours. The same pattern appears in sports, music, and other domains. This variance suggests that the journey to expertise is never a one-size-fits-all proposition, but rather a complex interplay between our genetic hardware and the software we develop through practice.

Chapter 2: Body Architecture: How Anatomy Shapes Athletic Destiny

In 1992, ophthalmologist Louis J. Rosenbaum encountered an unexpected problem while testing the Los Angeles Dodgers players' vision: they were literally off the charts. The commercially available eye charts he brought to spring training couldn't measure how well these athletes could see because nearly every player maxed out the tests. When he returned the following year with a custom-made visual acuity test that went down to 20/8 vision (near the theoretical limit of human sight), he discovered something remarkable—the average major league position player had right eye visual acuity of 20/11 and left eye acuity of 20/12. Mark Kipnis recalls the moment he first noticed his son Jason's extraordinary vision. During a ski vacation when Jason was twelve, Mark wanted to check a football score on a distant television. Too tired to walk across the large lodge restaurant, he asked Jason to go look. "He just turned his head and told me the score," Mark remembers, "and a little light went off in my head." Years later, Jason would be drafted by the Cleveland Indians and become their starting second baseman. When Australian sports scientists Kevin Norton and Tim Olds compiled data on athletes' body types throughout the twentieth century, they discovered what they called the "Big Bang of body types." Early in the century, elite athletes from different sports had remarkably similar physiques—a world-class high jumper and shot putter in 1925 were roughly the same size. But over decades, athletes' bodies diverged dramatically based on their sports. By the 1990s, the average elite shot putter had become 2.5 inches taller and 130 pounds heavier than the average international high jumper. This specialization extends to body proportions as well. Elite water polo players developed increasingly longer arms over time—growing more than an inch in arm length over two decades, five times the rate of the general population. Top swimmers like Michael Phelps have longer torsos and shorter legs, creating greater surface area in contact with water—like a longer hull on a canoe. Basketball players and volleyball players have short torsos with long legs for better jumping, while boxers often have long arms and short legs for greater reach with a lower center of gravity. These body type differences can have subtle but crucial effects on performance. Paula Radcliffe, the women's marathon world record holder, stands 5'8"—much taller than most elite female marathoners. While her size didn't prevent her from winning eight marathons during her prime years, it may explain why she struggled in hot conditions. Smaller runners have a larger skin surface area compared to their body volume, allowing them to dissipate heat more efficiently. In the scorching Athens Olympics marathon, Radcliffe collapsed while a 4'11" competitor took gold. The increasingly specialized body types required for elite success have made the gene pool within sports more narrow, even as it's become more global. As sports markets have shifted from participatory affairs to spectator events, the bodies required for success have become increasingly rare. This helps explain why athletic salaries have skyrocketed—we're paying for the scarcity of the physical attributes needed to excel at the highest levels. Understanding these anatomical realities doesn't diminish achievement but helps us appreciate the complex interplay between our genetic inheritance and the sports where we might find our greatest success.

Chapter 3: The Trainability Gene: Why We Respond Differently

Jim Ryun was a boy with a dream of becoming an athlete—any kind of athlete. He wasn't particularly interested in school, so how else could he distinguish himself but with his body? Yet his early athletic attempts were disappointing. He couldn't make the church baseball team because he was too weak to throw from third base to first without bouncing the ball. Despite being taller than most kids, he was cut from the junior high basketball team. By sixth grade, he was finding other ways to boost his self-esteem—smoking, fighting, and petty theft. In ninth grade, Ryun took one last shot at sports by trying out for the track team in the quarter-mile. He burst to the front for 200 meters before fading badly, finishing in just under sixty seconds—not good enough to make the team. Still, having briefly led the race gave him hope. When he entered high school the following fall, the cross-country coach's words at an assembly seemed directed at him: "Many of you boys may have done poorly in junior high sports, but don't be discouraged. Everyone grows at a different rate." Ryun joined the cross-country team and something remarkable happened. In his first mile time trial, he ran 5:38—not bad, but only fourteenth on the team. His concerned parents urged him to quit, noting how exhausted he always was. But Ryun persisted, and a dramatic metamorphosis began. Within six weeks, he moved up to junior varsity. Two months later, he led the varsity team to the Kansas state championship. The following spring, just six months after his 5:38 mile time trial, Ryun ran a mile in 4:26, defeating the defending state champion. By his junior year—only his second season of track—Ryun ran the mile in 3:59, becoming the first high school runner to break four minutes. Two years later, as a college freshman, he set a world record of 3:51.3. Ryun had gone from one of the sorriest members of his high school team to a world record holder in just four years. "I could not explain what was going on," he would later write. "Neither could anyone else." Science now offers an explanation. In the 1990s, a collective of five universities began the HERITAGE Family Study, putting 481 previously untrained people through identical five-month exercise programs. The results were astonishing: despite identical training, some participants showed little or no improvement in aerobic capacity while others improved by 50 percent or more. Statistical analysis showed that about half of each person's ability to improve with training was determined exclusively by their parents—by their genes. This phenomenon of "trainability" has been confirmed in multiple studies. When researchers put 24 sedentary young men through six weeks of cycling training, differences in the expression levels of 29 genes distinguished the high responders from the low responders. These genetic expression signatures predicted who would improve dramatically with training and who would struggle to make gains. Understanding this genetic component of trainability doesn't diminish the importance of hard work, but it helps explain why some people seem to transform rapidly with training while others struggle despite identical effort.

Chapter 4: Race, Ancestry and Athletic Performance

In 1986, Yale geneticist Kenneth Kidd received blood samples from the Biaka and Mbuti peoples of Central Africa at JFK Airport. These samples would help alter scientists' understanding of race and human ancestry. As Kidd analyzed DNA from populations spanning the globe, a consistent pattern emerged: African populations showed more genetic variation than populations from anywhere else in the world. In many areas of the genome, there was more genetic variation among Africans from a single native population than among people from different continents outside of Africa. This discovery supported the "recent African origin" model—that essentially every modern human outside of Africa can trace their ancestry to a single population that resided in sub-Saharan East Africa as recently as ninety thousand years ago. The intrepid band of our ancestors who ventured out from Africa might have consisted of just a few hundred people, taking only a tiny fraction of humanity's genetic diversity with them. As a result, people outside of Africa are descendants of genetic subsets of a group that was itself just a subset in Africa. This has profound implications for how we understand human diversity and athletic performance. In some cases, an individual's black skin might indicate very little specific knowledge about their genome other than genes for dark skin that protect against equatorial sunlight. One African man's genome potentially contains more differences from his black African neighbor's than does Jeremy Lin's genome from Lionel Messi's. Yet certain physical traits do show patterns related to geographic ancestry. Studies of Olympic athletes consistently find that those with recent African ancestry tend to have a more "linear" build than competitors of Asian and European descent—with longer legs and more narrow pelvic breadth. NBA data reflects this pattern: the average white American NBA player was 6'7½" with a wingspan of 6'10", while the average African American NBA player was 6'5½" with a 6'11" wingspan; shorter but longer-limbed. Australian geneticist Kathryn North discovered another intriguing genetic pattern related to athletic performance. She found that a gene called ACTN3, which produces the protein alpha-actinin-3 in fast-twitch muscle fibers, exists in different versions across populations. The functional version of this gene (the R variant) is nearly universal in West African populations, while about 18 percent of white Australians and 25 percent of East Asians have two copies of a non-functional version (the X variant). When North tested elite sprinters, she found that almost none had two X copies of the gene—they all produced alpha-actinin-3 in their fast-twitch muscles. The better the sprinter, the less likely they were to lack this protein. This pattern held true for sprinters tested around the world, from Jamaica and Nigeria to Finland and Greece. These findings don't suggest that genes determine destiny, but they illustrate how our evolutionary history has shaped human diversity in ways that can influence athletic potential along with countless other factors, including access to training, nutrition, and opportunity.

Chapter 5: Genetic Gifts: From Muscle Fibers to Blood Mutations

Around the turn of the millennium, a baby boy was born in Berlin with something unusual that caught the nurse's attention—he was twitching. Doctors worried about epilepsy, but pediatric neurologist Markus Schuelke noticed something else: the newborn had slightly bulging biceps, chiseled calves, and unusually defined muscles throughout his tiny body. Ultrasound examination showed he was beyond the top of the baby charts in muscle mass and beneath the low end in fat. By age four, this remarkable child could hold 6.6-pound dumbbells suspended horizontally at arm's length. Though not dramatically different from peers when fully clothed, his arm and leg muscles were approximately twice the size of other boys his age. This "Superbaby," as the media would later call him, had a condition that reminded Schuelke of something he'd seen before in certain animals. The mystery was solved when geneticists discovered the boy had mutations on both copies of his myostatin gene, leaving him with no detectable myostatin in his blood. Myostatin is a protein that signals muscles to stop growing—essentially a genetic "stop sign" for muscle development. Without this stop sign, the boy's muscles grew unchecked. Even more intriguing, his mother, who had one normal myostatin gene and one mutant copy, was a professional sprinter. This pattern of myostatin variation affecting athletic performance appears consistently across species. Racing whippets with a single myostatin mutation are significantly overrepresented in the highest competition levels. More than 40 percent of top-tier racing whippets have this normally rare mutation, while it appears in only 14 percent of second-tier racers and virtually disappears in the lowest racing grade. Dogs with two mutated copies become "bully whippets"—too muscular for sprinting but remarkably strong. Similar patterns emerge in racehorses. Two independent studies found that variations in the myostatin gene powerfully predict whether Thoroughbreds excel as sprinters or distance runners. Horses with a version that results in less myostatin earned five and a half times more prize money than their counterparts with normal myostatin levels. Beyond rare mutations, more common genetic variations affect how people respond to strength training. When researchers at the University of Alabama–Birmingham put 66 people on identical four-month strength training programs, the results varied dramatically. Some subjects' muscle fibers grew by 50 percent, others by 25 percent, and some showed no increase at all. This variation in response to training was linked to differences in satellite cells—stem cells that repair and build muscle—and to the expression levels of genes like MGF and myogenin. These genetic differences create natural advantages that training alone cannot overcome, suggesting that the most effective path to athletic excellence involves understanding and working with one's genetic gifts rather than fighting against them.

Chapter 6: The Heart of a Champion: Genetics of Endurance and Risk

It is December 2010, and human civilization in northern Scandinavia is temporarily reduced to a layer of sediment beneath the snow. The last few days have seen record snow and a constant -15 degrees Fahrenheit at the Arctic Circle in Finland—the Napapiiri, as the Finns call it—where I am now. There's no wind, so the first crunching step outside each morning is deceptively placid, before nose hairs morph into ice daggers. I'm driving north along highway E8, in search of a ghost. After three hours of driving from Luleå, Sweden, we pass through Pello, a town of four thousand. On our way out, we pass a granite pedestal atop which sits a larger-than-life bronze statue of a man in mid-cross-country ski stride. The man is Eero Mäntyranta, seven-time Olympic medalist and one of Finland's greatest athletes. We arrive at a cream-colored house on the west side of a large lake. As I step inside and kick the frost from my boots, an oddly Mediterranean face appears in the entryway. It is Eero himself, but I'm taken aback. In pictures from the 1960s his skin was perhaps slightly too dark for the Arctic, but now he is closer to the hue of cardinal red, mottled in places with purple. The contrast is stark when Eero's wife, Rakel, with her glacier blue eyes and alabaster skin, steps into the entryway. In the 1964 Olympics, Mäntyranta dominated cross-country skiing to such an extent that the media deemed him "Mr. Seefeld." In the 15K race, he finished forty seconds ahead of the next skier—a margin of victory never equaled in that event before or since. What made Eero special wasn't just his training or determination, but a rare genetic mutation. Throughout his career, medical exams showed he had extraordinarily high levels of hemoglobin and far more red blood cells than normal, leading to speculation about doping. Twenty years after his retirement, scientists discovered the truth. Eero and twenty-eight other Mäntyranta family members carried a mutation in the EPOR gene, which regulates the production of red blood cells. Of the 7,138 pairs of bases that make up the gene, there was a single base that was different in affected family members. This tiny alteration created a "stop codon" that caused the EPO receptor to be built without its normal braking mechanism. Without this brake, their bodies produced up to 65% more red blood cells than average, dramatically increasing oxygen-carrying capacity - a natural advantage for endurance sports. While Mäntyranta's story represents a rare genetic gift, other genetic variations can pose serious risks for athletes. Kevin Richards was a promising high school runner who collapsed and died after finishing second in a mile race. An autopsy revealed he had hypertrophic cardiomyopathy (HCM), a genetic disease causing abnormal thickening of the heart's walls. About one in every 500 Americans has HCM, though many never exhibit serious symptoms. For most health problems, exercise is miraculous medicine. But people with HCM can be at increased risk of dropping dead precisely because they exercise. Today, genetic testing can identify those at risk before tragedy strikes, allowing athletes to make informed decisions about their competitive futures. These stories remind us that our genetic inheritance shapes not just our potential for greatness but also the risks we face in pursuing it.

Summary

Throughout our exploration of the complex interplay between genetics and athletic performance, we've seen that the truth lies far from simple explanations. The 10,000-hour rule of deliberate practice fails to account for the dramatic differences in how individuals respond to identical training. Some people, like Dennis Rodman, can rise to elite levels with relatively little formal training, while others may train diligently for years with minimal improvement. Jim Ryun transformed from an average high school runner to a world record holder in just four years because he was what scientists now call a "high responder" - someone whose body adapts extraordinarily well to training stimuli. Our genes influence everything from muscle fiber composition to pain tolerance, from heart structure to oxygen-carrying capacity. The Mäntyranta family's EPO receptor mutation demonstrates how a single letter change in our genetic code can create Olympic champions. Yet most athletic traits involve complex interactions of hundreds or thousands of genes working in concert with our environments and experiences. The most profound lesson may be that understanding our genetic predispositions doesn't limit our potential but rather helps us chart more effective paths forward. By recognizing our natural strengths and limitations, we can tailor our efforts accordingly - perhaps avoiding sports that might trigger dangerous heart conditions, or focusing on activities where our body types and physiological responses give us the greatest chance to excel. In this way, genetic knowledge doesn't diminish human achievement but enhances it, allowing each person to make the most of their unique biological inheritance.

About Author

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David Epstein

David Epstein is the author of Range: Why Generalists Triumph in a Specialized World, and of the New York Times bestseller The Sports Gene, which has been translated in 21 languages. He has master's degrees in environmental science and journalism and has worked as an investigative reporter for ProPublica and a senior writer for Sports Illustrated. He lives in Washington, DC.

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