While I understand there are unknown unknowns, in science you can sometimes prove that something cannot be smaller or something cannot be bigger. Because it wou

While I understand there are unknown unknowns, in science you can sometimes prove that something cannot be smaller or something cannot be bigger. Because it would simply not be possible. Not sure if that's the case for DNA. And I am not talking about unknown unknown like some living organism using some other "substance" as the generic material.