Deliberate practice is a very specific category of activities that doesn't include most of what people think of as "practice." If you are a developer, having an open source side project does not count as deliberate practice. Deliberate practice for software development would be more like doing the hardest Project Euler problems in very constrained environments.

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Personally, I think it is very, very dubious that there are significant genetic components in virtually any activity. While having a relative that is good at chess might bias your probability towards being good at chess, this is not evidence that people without relatives who are good at chess will be bad at chess. The human genome is ludicrously small compared to the space of human activities. It simply cannot encode the skills necessary to be a pilot, to be a chessmaster, to be a doctor, a lawyer, a software designer, a lover, a fighter, or even a small, tiny fraction of the things humans do every single day.

It's perfectly possible that there is some cognitive process, like pattern recognition, that the Polgars were genetically predisposed to being good at. But since there are so few cognitive processes and so many skills, it's likely that there are huge swaths of talents that the Polgars would also be predisposed to as well as playing chess.

That's not even taking into account neuroplasticity, which we now know to be far more prevalent than we previously thought. Only decades ago it was thought that brains only deteriorate after a certain age. We know that to be false now. Beyond even that, technology is only going to become better, and we are very close (certainly on the timescale of humanity's existence) to true intelligence amplification on a biological level.

Further, the best way to find out if you're good at a thing is to do it. Self-fulfilling prophecies being what they are, it's best if you think you'll succeed going in, because otherwise you're literally sabotaging yourself. I think this is handled better by Cal Newport than by myself and I advise you to read his book So Good They Can't Ignore You for that handling.

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Ultimately, at some point in this discussion, you need to decide whether we live in the world of Limitless, or in the world of Gattaca. Either you spread the meme, whether it's literally true or not, that humans can accomplish anything, or you spread the meme that there are a handful of things you can do, and your only hope in happiness lies in finding those things and doing them.

Obviously I think it's better to live in the Limitless-world than the Gattaca-world. While I think that Gattaca is a woefully misinformed parody of genetic engineering on humans, it does a very good job of portraying a society where everybody thinks that they live in a caste and that's the end all and be all of their world.

If humanity had decided it was good at endurance hunting and gathering, we would still be on the Savannah. The story of humanity is the story of rejecting that there is a set list of things one can do, and doing things that are utterly impossible. Humans are the only thing we know of that can do this. If we abandon this, as far as we are aware, that light is snuffed out for the whole universe.

Until we know that is not the case, we need to be conservative, and guard that ingenuity with the utmost caution.