Did you read your source? This article you sent me is unsure of itself, admits multiple contradictions, and disagrees with what its findings are and how to use them. With the multiple contradictions, that the article admits, it couldn't even pass on as a scientific theory, much less as scientific precedent,
"It’s a question of their motivation. This is a tool, not the tool," he says of consumers. "If they're relying on the genetic test as the only performance indicator to tell whether they will do good or bad in sports, they're going to be disappointed, because it's not for that purpose."
"The results do tell you whether you have this protein in your muscle. That is clear. We have no idea if it contributes to performing at anything but an elite level. Even there, there are contradictions. We have very little information that it affects kids' performance."
"It's very similar to gene therapy in medicine. It hasn’t been successful in medicine and never studied in sports performance. It’s a real ethical dark zone, because there are medical concerns even pursuing it and no evidence that it would really work. Anti-doping societies have come out against it. It is definitely a concern."
Data is data, interpreting data is totally different, my interpretation is what the article admits - this proves nothing, and the research is incomplete.
But let's say for the sake of argument that it is reliable, (which it's not), the original argument is genetic differences among races, how can you say that not every race has the genes in the article? You can't, but you need to prove it to prove your original point.
P.S - On your African American selective breeding argument I respond by saying, that even if it did affect anything, (which it doesn't), humans breed selectively on their own, it has been happening since the beginning of time (for humans), every human wanted to mate with the most muscular or physically built of their kind, that's why men are attracted to women with big breast and women are attracted to tall men (height being a genetic trait). It has only stopped being that way in some countries of today.