My first response was pathetic :(

Let's consider biology. Physics and chemistry constrain biological processes and systems, for sure. But the number of distinct proteins based on the same set of amino acids, for example, is arguably unlimited (or at least, huge). Selection may favor one protein over another, and yet have virtually no impact on amino acid structure and diversity. Let alone on atoms, nucleons, quarks, etc.

The same applies to societies and cultures vs peoples.

So?

Physics is just emergent properties of ... (math?). Chemistry is just emergent properties of physics. Biology is just emergent properties of chemistry.

It's turtles, all the way.

No, you can opt out of the culture you were born into.

Sure, but if you're born in Canada and move to a city in China, then your phenotype is contributing to the cosmopolitan culture of that city, and the culture of the city is contributing to your phenotype.