Genetics and bodybuilding: Why some people build muscle more easily than others

If you spend enough time in a gym, you eventually start to notice something strange.

Two guys show up around the same time. Same age. Same height. Same weight. Same body-fat percentage. They train together, eat the same way, and follow the same program.

Six months later, one of them already looks like a superhero movie character, while the other just looks… a bit better than before, but nothing more.

In the fitness world, there’s a ready-made answer for this:

“Genetics.”

A magic word. A catch-all word. And above all, a word that saves you from thinking any further.

But when you start looking at bodies through a morpho-anatomical lens, you realize the truth is far more precise, and far more brutal.

The kind of genetics in bodybuilding no one ever analyzes

When people talk about genetics in bodybuilding, they think about hormones, recovery ability, metabolism, testosterone levels, and the capacity to build muscle.

But in the gym, the kind of genetics that really stands out isn’t invisible. It’s right in front of you.

Look at an actor like Chris Hemsworth in Thor. Or Michael B. Jordan in Creed. Or Henry Cavill in Superman.

Before you even talk about muscle, you can see:

• a thick rib cage

• wide clavicles

• arms that look naturally “full”

• shoulders that seem to spill outward

  
  

That isn’t just muscle. That’s architecture.

Going back to the two guys from the introduction who signed up at the gym together and look almost identical on paper, what really changes is not the amount of muscle — it’s the amount of space their skeleton gives that muscle to express itself.

A slightly philosophical way to put it, I know… but by the end of this article, it will make perfect sense.

The body is not a pile of muscles, it’s a system of levers

In bodybuilding, we talk about pecs, lats, quadriceps. But in reality, the body works like a system of levers.

Your bones are lever arms. Your joints are axes of rotation. Your muscles are engines pulling on that structure.

Two people can perform the same bench press with 100 kg… and yet create completely different mechanical stress.

An athlete with:

• short forearms

• a thick rib cage

• low tendon insertions

will have a short, compact, mechanically efficient movement, and therefore a higher-than-average potential for muscle development.

Guys who have strong bench presses generally share very similar structural and morpho-anatomical traits. Relatively short forearms and a large, deep rib cage.

Another person with:

• long arms

• a flat rib cage

• and narrow shoulders

  
  

  will perform a much longer movement in terms of range of motion, with more torque on the shoulders and less direct tension on the pectoral muscles.

I would be curious to see whether the prodigy Wembanyama would even be able to perform decently on the bench press, with such a flat rib cage, extremely long arms, and only average shoulder width.

Same load. Same exercise. Two different physical realities. Two different rates of progress.

Why some people build muscle “more easily”

In bodybuilding, we love to say that some people are “genetically gifted,” the so-called “Golden Genetics,” a nod to Marvel Fitness.

But what we really observe is that some people have a structure that naturally places their muscles in mechanically advantageous positions.

Take Ronnie Coleman. Even before talking about his insane loads, look at his clavicles, his rib cage, his humerus-to-forearm ratio, and his muscle insertions. His skeleton was the perfect platform on which to build a titan’s physique.

Ronnie Coleman: a blessed structure, advantageous limb proportions, and optimal muscle insertions.

Conversely, some extremely strong athletes will always struggle to “fill out” certain areas, not because they lack effort, but because their geometry works against them.

Dwayne Johnson: an outstanding physique and a mountain of muscle, yet you can tell at first glance that certain morpho-anatomical traits will never make him a Mr. Olympia.

Hypertrophy is not just a matter of effort. It is a matter of how force travels through your structure.

The great injustice of modern fitness

Bodybuilding sells a comforting idea:

“If you follow the right program and eat properly, you’ll get the same results as everyone else.”

That’s false. And not because some people “work less” or “recover better.” It’s false because we confuse the program with the structure.

It’s like giving everyone the same pair of shoes and saying, “Walk, run, jump, it will work for you, just like it worked for others before.”

For some people, it’s true: the shoe fits perfectly, the stride is natural, the support is stable, and there’s no pain. For others, it pinches, rubs, and alters the way they move… and in the end, we blame the person for having “bad technique.”

In bodybuilding, it’s the same. The same exercise, the same load, the same tempo do not create the same stress, the same tension, or the same risk, because the mechanical supports are not the same.

Morphological potential

Every body has what I call a morpho-anatomical potential.

It is not a ceiling. It is a map.

It tells you:

• which areas will respond quickly

• which will require strategy

• which exercises are naturally made for you

• which will always be ungrateful.

When you ignore this map, you train in the dark. When you understand it, everything changes.

Toward a smarter form of bodybuilding

The future of training will not be a new protein or a miracle supplement.

It will be something simple, but radical:

understanding the geometry of bodies.

Measure. Compare. Classify. Adapt.

The day we stop treating all bodies as identical, stagnation will stop being the norm.

And on that day, many people will finally realize that their body was not broken. It was simply misunderstood.

Once again, thank you for reading, and feel free to leave a little heart if this article helped you better understand the subtlety of morpho-anatomy applied to bodybuilding.

Until then, train well, and see you next time.

Take care,

Corentin.