Are there really such things as sports genes?

I’ve seen many articles with the following:(below). My question is this. Is this real science? I look forward to your feedback

Alpha-actinin 3 (ACTN3)

"The Power genes
The following 4 gene variants have been the most researched when it comes to to influencing power performance. They are the following:

ACE I/D, ACTN3 R577X, IL6 -174 G/C, and NOS3 -786T>C"

"How is ACTN3 involved in sporting performance?
Everyone has two copies of the ACTN3 gene, with one copy inherited from each parent. In any one gene there may be subtle variations.

Scientists have found a variant, known as R577X, in the ACTN3 gene, that alters the way the body reads the ACTN3 gene instruction. As everyone has two copies of the ACTN3gene, there is 3 different combinations or Sports Performance Types.
XX - TYPE : You have the R577X variant present in both copies of your ACTN3 gene. Studies of elite level athletes from the Australian Institute of Sport (AIS) show, that this combination is associated with a natural predisposition to endurance events.

RR - TYPE : You do not have the R577X variant present in either copy of your ACTN3gene. The absence of the R577X variant from both copies of the ACTN3 gene is associated with a natural predisposition for sprint-power events.

RX - TYPE : You have the R577X variant present in one of the two copies of your ACTN3gene. If you have this combination you may be equally suited for both endurance and sprint-power events."

There are certainly genes that affect athletic performance, but you should always be skeptical of any claims that a single particular gene does anything. Most traits, especially traits as vague as “athletic ability”, are the result of the interactions of a great many different genes. Even if one or two particular genes are known to be correlated with athleticism, the correlation is going to be pretty weak.

I don’t know about specific genes, but I do know some people are ‘born with it’. When about 33 YO, I attended a US Air Force school. We had to run 1.5 miles every couple of days. I was a pretty good runner in those days - I thought. There was a 40+ YO, pot-bellied, chain smoker in my flight. I was afraid he would die running the 1.5 miles.

He damned near beat me and I had to run hard to keep ahead of him.

Turns out that he was the Georgia State champion in the mile in high school. He also claim to not running or any other exercise at all in the last year.

Genetics had to do something with his ability to run so fast.

I looked up some of the studies on PubMed. The original study looked for these ACTN3 variants in elite Australian athletes (those who compete in the Olympics or other international competitions). In short, they found that sprint/power olympians had 50% RR, 45% RX, and 6% XX genotypes. Endurance athletes had 31% RR, 45% RX, and 24% XX. In their control group, there was 30% RR, 52% RX, and 18% XX. They also found interesting differences between the distribution of these genotypes in male and female athletes in each group.

The most biologically significant difference, in my eyes, is the lack of the XX genotype in sprinters (it was completely absent in female sprinters). So if you’re XX, you probably don’t have a great shot at being an Olympic sprinter. Otherwise, even at this top level of athleticism, while the differences are statistically significant they don’t seem particularly big to me.

Skimming through other studies, I found another that said that there is no significant association between these genotypes and athletic performance if you take a sample of non-athletic young adults. So these genotypes by themselves do not confer any particular athletic ability.

In summary, there are definitely genetic variants that contribute to athletic ability, but each on their own doesn’t make much of a difference. It’s only the combination of many many different genes and environmental factors that add up to any real “innate” athletic ability.