That sounds like less of a wrong question and more of a "right question with surprising (low prior) answer". As far as the asker knew, the answer could have turned out to be, "Genes produce the same organism phenotype across virtually all environments, so genes are more important because changing them is much more likely to change the expressed phenotype than changing the environment." (and indeed, life would not be life if genes could not force some level of environment-invariance, thereby acting as a control system for a low-entropy island)

I don't see what's wrong with answering this question with "neither [i.e., they're equal], because they jointly determine phenotype, as independent changes in either have the same chance of affecting phenotype".

An example of a wrong question, by contrast, would be something like, "Which path did the electron really take?" because it posits an invalid ontology of the world as a pre-requisite. The question about phenotypes doesn't do that.