Genes and Sport: Are Your Parents Responsible for Your Wins and Losses?

We all know of champion athletes whose parents and perhaps grandparents were also champions. Moreover, racehorse owners spend millions of dollars on stud fees to breed winners.  This seems to tell us that champions are born and that if you don’t have the champion gene, you can never be truly successful, no matter how hard you train. In other words, you must be wasting your time practicing your favorite sport if your parents were not champions themselves. But if champions can be bred, why don’t all racehorses bred for performance become champions? The reason is that there are factors other than heredity that play important roles in performance, too.

Genes Are More or Less Important

There is no getting around it; genes determine our potential for developing many of the structural and functional characteristics important in determining sport performance. For instance, to be a successful center in the National Basketball Association, you must inherit the gene for tall stature.  For other characteristics, though, diet, training, and other environmental factors play a huge role in how your genetic potential is expressed. For example, you may have the genetic potential for a low body weight, but eating too much and exercising too little can overcome that genetic message and cause you to become obese. Thus, some characteristics, like height, are strongly influenced by genes, whereas others, like abdominal girth, are less affected by the genes and are more likely to be influenced by the environment. Table 1 illustrates how strongly the genes typically affect some of the structural, functional, and performance characteristics of the body. Those characteristics in the table for which the genes have only a low to moderate effect (e.g., balance, reaction, time, accuracy of movements) are likely to be more powerfully influenced by training, diet, and other environmental factors than are characteristics like strength and flexibility, for which the genes have a large effect.

 TABLE 1.  Effects of Genes on Structure, Function, And Performance



Height, Length of Arms


Waist Girth

Small to Moderate

Muscle Size


Muscle Fiber Composition (Fast- and Slow-Twitch)


Mitochondria/gram of Muscle


Heart Size


Lung Size and Volume


Activities of Muscle Enzymes Used to Produce Energy

Small to Moderate

Resting Heart Rate


Blood Pressure


Air Flow in Lungs


Muscular Strength


Muscular Endurance (e.g., pushups, pull-ups)

Moderate to Large

Movement Speed




Flexibility of Joints


Reaction Time

Small to Moderate

Accuracy of Movements

Small to Moderate

Aerobic Endurance (e.g., distance running or cycling)

Moderate to Large

Anaerobic Power (maximal cycling power output in 10 seconds)


The genes also determine the speed and extent to which your body’s performance characteristics respond to training, diet, and other environmental factors. For a given characteristic, such as aerobic endurance or muscular strength, some people are strong responders to training and others are moderate to weak responders to the same training. What this means, for instance, is that even though your genetic potential for distance running may be less impressive than that of a competitor, you may be able to develop that potential more quickly and completely by training hard so that you can always beat your opponent. There is insufficient published research on how strongly genes affect an individual’s response to training to be certain, but Table 2 lists some of the early conclusions from this research. 

It is likely that the small genetic effect on the response of strength to resistance training will be greater when studies are completed with larger numbers of subjects. The training effect on power output in 10 seconds was only weakly affected by the genes, possibly because technique and reaction time, both little affected by genes, are more important than raw strength, more strongly affected by the genes.

TABLE 2.  Effects Of The Genes On Responses To Exercise Training





10-Second Maximal Power Output-Bicycle Ergometer


90-Second Maximal Power Output-Bicycle Ergometer


Aerobic Endurance

Moderate to Large

Tactics and techniques, such as drafting and using an aerodynamic body posture in cycling, are critical to success in many sports but are not affected by the genes. Champions at the elite level must be experts at tactics and technique in addition to possessing the necessary genetically determined attributes for success in their sports. Still, less genetically gifted athletes who are talented in tactics and technique may become champions at non-elite levels of competition.


Whether you can be a champion is determined by 1) many of your structural, functional, and performance characteristics before training, 2) proper training, rest, and nutrition, 3) the speed and extent to which these characteristics adapt to training, and 4) your mastery of tactics and techniques in your sport. It is probable that elite athletes are those who begin with high levels of the characteristics needed for success in their particular sports, have large responses to training in those characteristics, and have mastered the necessary tactics and techniques. However, at a less than elite level of competition, you can compensate for a “non-gifted” genetic potential with optimal training and nutrition and by mastering the tactics and skills required for excellence in your sport. For a given individual, it is not possible to predict whether or not or the extent to which a characteristic such as vertical jumping ability will respond to training.  Moreover, many athletes reach a point where they have to train more often and harder to obtain fewer and fewer performance benefits. When athletes reach this point, it is possible that they are approaching their genetic limits.

Although your genetic background can influence how successful you might become in a particular activity or sport, this background is probably too complex to be fully known or understood. The possibility of a magical altering of the genes by genetic engineering is very unlikely because many genes are involved, there are interactions among different genes, and there are interactions between genes and the environment.

Reprinted with permission from the Gatorade Sport Science Institute Volume 14 (2001), Number 4. For additional information:


Bouchard, C., R. Malina, and L. Perusse (1997). Genetics of Fitness and Physical Performance. Champaign: Human Kinetics, pp.1-400.

Bouchard C., et al. (1999).Familial aggregation of VO 2 max response to exercise training: Results from the HERITAGE Family Study.  J. Appl. Physiol. 87: 1003-1008.

Skinner J. S., et. al. (2001).  Age, sex, race, initial fitness, and response to training: The HERITAGE Family Study.  J. Appl. Physiol. 90: 1770 – 1776.

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