It's more the other way around. People are guessing X,Y, Z due to the axes. While we know the X and Y most likely stand for the chromosomes due to the Japanese logos having a DNA strand on them.
I don't know, the chromosome theory doesn't make much sense to me.
As far as I'm concerned the X and Y are stylized because they didn't just want to slap colored letters on there, they wanted to make it slightly stylish. XYZ, actually makes sense in the context of what the game was shown to be about.
How do you get Chromosome when the games are in full 3D, and the legends represent X,Y, which would mean that there would likely be representation of Z, for the 3 dimensional field of X, Y, Z.
DNA would make sense for Pokémon however, I won't deny that, I'll give that to you. Just seems awkward to do it in this particular sense.