Dr. Jim Stoppani Interview: “Genetics Are a Huge Role In Everything”

In episode eight of his interview with Generation Iron and BarBend, Stoppani explains the importance of genetics.

Episode eight of Generation Iron and BarBend‘s interview series with exercise physiologist and JYM Supplements founder Dr. Jim Stoppani aired on Generation Iron‘s YouTube channel on April 11, 2022. Stoppani’s interview with moderator Vlad Yudin has spanned the gambit of fitness and nutrition from contralateral, pre-exhaust training, and high-intensity interval training (HIIT) to carb-cycling, intermittent fasting, and benefits of meal prepping and various diets like keto.

In the eighth episode of Stoppani’s interview, Yudin inquired about the impact of genetics on bodybuilding and reactions to performance-enhancing drugs (PEDs). Check out what Stoppani had to say in the video below, courtesy of Generation Iron‘s YouTube channel:

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Genetics Can Define You

Yudin wastes no time asking about genetics inherent influence on training and aesthetics. He asks Stoppani if someone’s genetics can leave them more prone to higher body fat, prevent them from looking fit, or if it’s just an excuse.

Stoppani doesn’t doubt that genetics play a role. He laughs about the premise of walking around the Arnold Classic and seeing a lean 6-foot, seven-inch tall, 400-pound giant and a five-foot, two-inch tall person who weighs 75 pounds in the same room.

The variation of the human body is insane.

Stoppani discusses two types of genes – phenotype and genotype. The former are observable characteristics of a person, such as eye color and height, while the latter is their genetic makeup. (1)

In terms of sports like bodybuilding, Stoppani mentions that genetics are referenced constantly:

They’re gifted, they’re gifted, they’re gifted. These are extremes.

Elite athletes often have more “extreme” genetics that are advantageous in a competitive environment. Some examples of this genetic predisposition might be levels of muscle mass, leanness, capacity to lose body fat, or how one’s cardiovascular ability is affected by how many red blood cells they naturally produce.

Even the number of natural fast-twitch muscle fibers in the muscles is critical to excel in a particular sport. Stoppani uses the example of an Olympic speed skater needing “more fast-twitch muscle fibers in their legs coming out of the womb.”

Genetics are a huge factor.

Stoppani suggests that someone’s genetic predisposition is predictive of their athletic capacity.


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Performance-Enhancing Drugs

Stoppani suggests further that genetics influence how someone will react to performance-enhancing drugs — or any drug. Some bodybuilders might respond terribly to a specific drug cycle that produces negative results or health complications. Others may never endure any adverse side effects for their entire careers, even if their diets and training regimens are similar.

Same thing with smoking. There are people who smoke all their life, and never get lung cancer.

Stoppani references Shawn Perine, the VP and Editorial Director of the AMI Fitness Group (including Muscle & Fitness, FLEX, and Muscle & Fitness Hers magazines), who died in December 2017 after being diagnosed with stage four lung cancer despite following a vegetarian diet and never smoking in his life.

Genetics are a huge role in everything.

While discipline, a strong work ethic, and a good diet and training program are essential for elite bodybuilders to ascend to the top of the sport, it seems that there is a natural buy-in of favorable genetics required first.


  1. Nussinov, R., Tsai, C. J., & Jang, H. (2019). Protein ensembles link genotype to phenotype. PLoS computational biology15(6), e1006648. https://doi.org/10.1371/journal.pcbi.1006648

Featured image: @jimstoppani on Instagram