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How to know if you have good or bad genetics for muscle growth?

Updated: Apr 14

Genetics matter for pretty much any sport, and this especially applies to strength training. Roughly around 40%-60% of most aspects of your body are genetically predetermined. However, ''poor genetics'' is often used as an excuse by many for lack of progression. Cannot lose weight? Its bad genetics, my hormones do now allow me. Cant build more muscle or strength? Again, bad genetics. It becomes an easy way to justify lack of results, and shifts the focus from actually looking back and analyzing your current program to see what is wrong with it.

The truth is, if you are most likely to fall in the average category when it comes to your genetic potential for muscle growth. Yes, if you are an outlier, you might fall in either a bad or extremely good genetic group, but that is unlikely. Luckily, science allowed us to understand what makes us genetically good or bad for strength sport and building more muscle.


Let us start with the base foundation of it all, the DNA. DNA is a blueprint to your body that contains all the information to construct the body. This could give us the most precise information about the ability and potential of each person, however the science in its current state is nowhere near ready enough to give practical results.

A good DNA test nowadays looks at 20 genes, however we have more than 20 thousand genes in our body. To add even more complexity to this, its the interaction between these genes and many other factors in your body (like enzymes) that determines the practical outcome. So looking at the single gene probably does not paint the whole picture.

Currently the sport industry also does not rely on DNA testing for talent identification as it simply is not developed enough.

Secondary sex characteristics (male)

These are features that first appear during puberty. They can be a good indicator of testosterone levels which is highly correlated with muscle growth.

  1. Hairy body (face, forearms, abs and chest)

  2. Baldness (derivative of testosterone, DHT, causes top of the head to go bald)

  3. Deep voice

  4. Square face


By frame I mean your bone structure. The bigger the bone frame, the more muscle you can put on the frame. Mainly this means how thick your bones are. For example, Olympic weight lifters have very thick wrists and ankles, and this is a very strong predictor for success.

However, most people have a mix of weak and strong body parts. If you want to measure your muscular potential with this method, you can use the data below as a reference.

Wrist circumference size

2D : 4D Ratio

The ratio is calculated by dividing the length of the index finger (preferably right hand) by the length of the ring finger of the same hand. The lower the ratio, the higher the potential for sports.

Length of muscles

Muscle length determines the maximum potential you can achieve with that muscle group. A good example would be biceps and latissimus dorsi length. As you can see in the photos below, there is a drastic difference between the two photos below. On the first photo the lats go way lower than on the second photo, and this is primarily determined by genetics (you cant alter the length of your tendons).

Lats with low insertion points

Lats with high insertion points

Similarly, biceps size and shape is also determined by the length of the tendons. You can easily determine this by flexing your biceps to 90 degrees and measuring how many fingers can you fit in between your biceps and elbow. The more fingers you can put, the worse genetics you have for building huge arms.

Birth weight

Being born as a heavy baby can indicate a stronger muscular potential later on. For the reference we can use the average weight for newborns which is 3.4 kg. Anything above this would be considered above average and anything below 2.5 kg would be considered underweight.

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Different body types will affect the technique used for big compound lifts like bench press, squats and dead-lifts. For example somebody with a short torso will probably find it easier to squat with a more forward lean to maximize his power output. On the other hand, people with long torso usually squat more upright. If you want to go extreme, you can compare 2 world record holders that use completely different technique for squats.

This is why you should never just copy someone else's technique and why I always preach that a good technique is a ''range'' which depends on many different factors such as your training goals, body type and injury history.

Forward lean vs upright squat

My own thought

Based on my own experience working with hundreds of clients so far, genetics does play a big role in how quickly you build muscle. Scientifically it has been shown that this difference can be up to seven fold. There are similar finding for strength progression as well.

The biggest question here is how much of it is in our control? The simple answer is a lot. First of all there are many different variable in the mix like different training programs, different levels of effort, consistency, levels of stress, sleep hygiene etc.

This is why I am very cautious when thinking about this topic because if you only focus on the things you cannot really control, it can create a sense of helplessness, and that can translate into not doing anything at the end. Yes, some people have better genetics and better leverages for lifting weight, but that applies to literally everything in life. That does not mean you do not have any control on where you end up. You do not have to be a world record holder in squat to look good and be healthy. Instead of comparing yourself with others, you can be your own competition and implement a growth mindset. In my opinion, those small incremental improvements make the whole difference over time.

I will use myself as an example. In my opinion, I have average to slightly below average genetics depending on my body parts. Very small bone frame that limits the amount of muscle that I can put on. However, if you look at my comparison photos I still managed to build a decent physique compared to my starting point.

Instead of throwing in the towel and blaming your genetics, you still have a lot of control over how much you can change the way you look. The best starting point would be to re-evaluate your workout and nutrition program as well as any lifestyle factors that could potentially interfere with your progression.

If you want to take action today and take your fitness to the next level feel free to book a free assessment call with me.

What you will get from this call:

  1. I will see what is your current situation and give you my feedback on what is the best way to go forward.

  2. You will understand exactly what  needs to be done in order to achieve your desired fitness goal.

  3. We will talk about strategies that can help you to reach that goal and how to fit them in your lifestyle.

  4. If we both feel that my program and my coaching is a good fit for you, we can talk about working together.


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