Yes, DNA was non-existent in their minds but it wasn't non-existent. It was invisible to their eyes but it was never invisible.<quoted text>
DNA was non-existent in the minds of people back then. Their realities did not have DNA in them at all. The "knew" about other things, like miasma and the inheritance of acquired characteristics.
The thing is, everything about the way they interacted with, experienced and thought about the world around them included non-DNA causal explanations of how life worked. Their lived reality was very different than our own.
I think as we progress in the next few hundred years, God will become more & more less "invisible" and "non-existent".