The Great Debate: Genes vs. Practice

We’ve all heard the argument of deliberate practice, developed by the psychologist Anders Ericson, then made famous by Malcolm Gladwell: that with 10,000 hours of deliberate practice you can become an expert at any skill. However, your inner skeptic is probably telling you that no matter how much you want to dunk like LeBron James, no amount of deliberate practice is going to get you there.

So who is right? Well, both of them, sort of…

Tony and Chris have already written about deliberate practice. A quick summary is this: Deliberate, quality, and variable practice routines matter only until you reach elite levels, where the variability in performance attributed to practice lowers to about 1%. Once we get to the elite level other factors come into play namely, genetics, environment, and practice consistency.

“Well, we have our answer. Pack up your bags, all else being equal having good genetics is what makes you elite and I don’t have the genetics to be elite, so I am going to quit.”

In the infamous words of Lee Corso “Not so fast my friend!”


The things that we eat, our training regimens, the quality of our sleep, basically everything we do in our daily lives has an effect on the way that our genes get expressed and therefore how well we can perform as an athlete.

Our bodies are constantly “sampling” our environment and making molecular changes based on what input it receives. This is termed epigenetics. Epigenetics is a growing field of study in science and the research is increasingly expanding to athletes.

I go into much more detail on the science of epigenetics in a blog post on my website here, but for the purpose of this article, we can summarize epigenetics as a dimmer switch that turns the expression of certain genes up or down based on environmental input.

Epigenetics doesn’t change the actual DNA sequence, instead, it changes the number of proteins that a certain gene will produce which leads to a change in a person's phenotype: your actual physical characteristics.

Is this machine broken?

In a great example of epigenetics at work, a fantastic study1 was conducted to see if epigenetics could help to explain why exercise makes us healthier.

Because genetics, gene expression, and epigenetics are supremely complex and are regulated by many factors, designing a study that can isolate epigenetic changes is extremely difficult. So, the authors came up with an ingenious solution. They had participants do an endurance exercise, bike pedaling, for 45 minutes 3 times per week — using only one leg.

Basically, they had made each person their own control group (one leg being trained and one untrained) which balanced all factors outside of the bike pedaling intervention. They then took a tissue sample from both legs before training and after 3 months of training.

As a side note, I would have loved to been a fly on the wall watching people peddle on a bike designed to use only one leg. Throw in some Benny Hill music and I would have been crying laughing.

Anyway, the results showed that after 3 months participants had a large increase in DNA methylation—an epigenetic change—on genes associated with muscle metabolism and remodeling. The participants also had a change in the expression of over 4,000 genes total in the exercised leg versus the stationary leg.

Other studies2 have shown that starting an exercise regimen in previously sedentary individuals changed the expression of over 7,000 genes. On average we have 23,000 genes. That is a change in expression of greater than a 1/4th of a person’s entire genome from a standard exercise regimen.

We are given our genetic baseline at birth. We have an upper limit of our abilities from the day we are born. However, through epigenetics, we can stretch that limit further. We do have a physiologic ceiling, at least currently. New research into gene editing (basically inserting new DNA into specific parts of your existing DNA), may soon give us the ability to change even that inherited upper limit.

The underdog story

Everyone loves a good underdog story, so it is hard for us to believe that our genes, rather than dedicated training, may be the largest factor in athletic success. However, with epigenetics, we can see that it is possible to impact even the genetic component of performance. In his book, The Sports Gene, David Epstein chronicles the stories of two high jumpers at the 2007 World Championships: Stefan Holm and Donald Thomas. Holm is supremely short compared to many professional high jumpers at 5'11". However, Holm had performed untold hours of deliberate practice, perfected his technique, and had slowly improved over 20 years of training. In 2005, after a lifetime of dedication, he won the World Championships.

Thomas, on the other hand, had been high jumping for only 8 months after his natural jumping ability had been brought to the attention of a track coach.

With only 8 months of experience and laughable form, Thomas remarkably defeated Holm to win the 2007 World Championship.

Now, I would assume many people’s reaction would be that of disappointment for Holm. However, mine was the complete opposite. When researchers examined the Achilles tendon length of both athletes (the longer the Achilles tendon, the more energy it can store for jumping) they found that Thomas had an extremely long Achilles tendon compared to his height, but that Holm’s was extremely average.

However, and this is the part that I find more fascinating than Thomas's performance, Holm had a remarkably stiff Achilles tendon. How stiff an Achilles tendon is can also affect the jumping ability.3 Unlike, tendon length, Achilles stiffness can be increased through training.

Holm, through increased training and deliberate practice, had caused epigenetic changes to his physiology that allowed him to compete at 5'11", on an international level with some of the world's most genetically gifted jumpers.

Epigenetics can be a tool our bodies use to compensate for a lack of inherent genetic talent.

Case Closed

The fun is over and now I have to pick a side for the winner of the great debate of genes vs. practice. Sadly, I am going to take the easy road and say both points, as in most debates, have legitimate claims that are backed by research.

As with Stefan Holm, we can improve our physiology through consistent, dedicated practice and epigenetic changes. However, there will always be a Donald Thomas waiting in the wings to unleash their raw genetic talent.

My personal philosophy is that we may not all be able to compete at the Olympics or at a professional level, but that we all have the ability to become a legend in our own worlds, however you choose to define that.

I want to thank Tony and Chris for allowing me this space to provide some, hopefully, useful and interesting information for you. If you liked this content, please check out my Podcast: The Precision Performance Podcast on iTunes, stitcher, or wherever you get your podcasts from. You can also see more material over at

Much love,


  1. Lindholm ME, Marabita F, Gomez-Cabrero D, et al. An integrative analysis reveals coordinated reprogramming of the epigenome and the transcriptome in human skeletal muscle after training. Epigenetics. 2014; 9(12):1557-1569
  2. Rönn T, Vokov P, Davegardh C, et al. A six Months Exercise Intervention Influences the Genome-wide DNA Methylation Pattern in Human Adipose Tissue. PLoS Genet. 2013; 9(6): doi: 10.1371/journal.pgen.1003572
  3. This also has a genetic component based on the body’s ability to produce collagen, another protein in the body. Holm likely had increased collagen producing genes as well, but the point remains valid.