My old boss used to say, "You know, God made us (humans) all about the same." Sure, it is often said that humans, when compared genetically, are about 99.9% similar, however there are still some pretty remarkable variances between how we look and perform.
The 99.9% similarities between us controls things as common as having skin, hair, teeth, a stomach, high-level brains, etc., but can had differences in how those things look and work. For example, how tall we are, how long our limbs are, how big our noses are, etc. We also mostly act the same too - although this is heavily influenced by your surroundings.
If you keep looking deeper into that rabbit hole you can begin to understand that not only do our muscles oftentimes look differently, but they can act and perform differently as well. I always say to people, "You can't choose your parents," because your genetic lineage can have a drastic outcome on all of these factors that influence you. Some folks are able to build big muscles. It just comes easy (easier) to them.
So what about athleticism? Do you remember growing up and playing with your friends? Do you remember that one friend of yours that just seemed to be better than everyone else at everything (or most things)? They could run faster, jump higher, were better at Mario Kart, and could be the best with little to no effort at all! Was this friend in the gym spending hours a day getting bigger, faster, and stronger? Of course not, they were just gifted in ways that maybe you weren't. The effectiveness of their neural pathways were better than yours. They had better coordination, better strength, better reaction time, etc.
Why are some people so good at some things? Is it because they work harder? Is it because they are more committed? Possibly, but not necessarily.
Take this review, for example:
Environmental and genetic factors influence muscle function, resulting in large variations in phenotype between individuals. Multiple genetic variants (polygenic in nature) are thought to influence exercise-related phenotypes, yet how the relevant polymorphisms combine to influence muscular strength in individuals and populations is unclear. In this analysis, 22 genetic polymorphisms were identified in the literature that have been associated with muscular strength and power phenotypes. Using typical genotype frequencies, the probability of any given individual possessing an "optimal" polygenic profile was calculated as 0.0003% for the world population. Future identification of additional polymorphisms associated with muscular strength phenotypes would most likely reduce that probability even further. To examine the genetic potential for muscular strength within a human population, a "total genotype score" was generated for each individual within a hypothetical population of one million. The population expressed high similarity in polygenic profile with no individual differing by more than seven genotypes from a typical profile. Therefore, skeletal muscle strength potential within humans appears to be limited by polygenic profile similarity. Future research should aim to replicate more genotype-phenotype associations for muscular strength, because only five common genetic polymorphisms identified to date have positive replicated findings.
So although this isn't ground-breaking or particularly new, we are starting to discover just how advantageous you may or may not be due to the genetic lottery that you have played when you were born. The above review details 22 genes (that we know of) that are beneficial for strength and power performance in individuals. In these 22 genes, the more you personally have, the greater likelihood you have to being a strength or power athlete.
There are 3 "options" when it comes to these gene phenotypes. You can either have a favourable gene expression, a neutral expression, or a negative expression. In other words, whether or not you have a specific genotype can either make you good at something, potentially bad at something, or no real positive or negative effect at all.
One well-known gene, for example, is one that encodes for the protein ACTN3 has been shown to be favourable for sprinting (in those that contain the correct gene), and can actually be favourable for endurance athletes with a mutated ACTN3 protein.
Studies have linked the fiber twitch type with ACTN3, i.e. fast twitch fiber abundant individuals carry the non-mutant gene version. Also, studies in elite athletes have shown that the ACTN3 gene may influence athletic performance. While the non-mutant version of the gene is associated with sprint performance, the mutant version is associated with endurance.
What's notable in the above review is that the researchers calculated 0.003% of the population to have "optimal" gene expression for strength and power attributes. This certainly makes sense, especially in a country like Canada - population around 30,000,000, that about 9,000 individuals (give or take) have more optimal strength and power characteristics.
Does this mean that other individuals can't be strong and powerful? Absolutely not, but those individuals with favourable genetic phenotypes are certainly at an advantage when it comes to producing strength and power. On the flip side of that coin, as we have seen with ACTN3, it is entirely possible to be not all that great at something.
It should also be noted that although an individual may have a genetic potential for something, does not mean that they are going to be the best. Although this number has been associated with strength and power, let's use the same figure (for argument's sake) to discuss genetic potential for other attributes as well. Assume that even at 0.003% of the population has a genetic advantage for something, that still creates a lot of competition between yourself and the other "elites" in that category. Being strong and powerful, especially compared to your less-than-genetically-gifted friends will only take you so far. If you wanted to compete on an Olympic level, for example, then you still need to hone your skills and work hard to be even better than those around you.
I will once again remind my readers that this is not to sound like an old curmudgeon, saying that talent and athleticism is "all luck." There is certainly advantages that make some of us better than others at certain things. It is not impossible, just highly unlikely that you would see a 7 foot tall man competing at the Olympic games in weightlifting. The limb lengths and joint angles are not as advantageous for maximal torque and power required for Olympic lifting. On the other hand, although we have seen some shorter individuals play in the NBA before, the game certainly favours taller individuals. Being tall, or having a long torso (advantageous for weightlifting) cannot be trained. If, however, you are tall, and you work hard, then you have a chance to make it big.