You have protein particles and prions, that that replicate and contain a very primative code that is not DNA but thought to be a precursor of what eventually evolved into DNA.
Right there is a huge logical fallacy.
Just because there thousands of codes and languages created by intellegence does necessarily mean that ALL codes and languages were created by intellegence.
DNA could easily have evolved naturally and scientific research into it has discovered primitive replicating proteins thought to be precursors to the much more complicated DNA. Prions (such as that which causes Mad Cow Disease) are even more primative then virus' and contain code that may have developed into DNA. I am not that knowledgable on cellular biology and evolution so I'm only scratching the surface with what I remember reading and I could be wrong but I don't think so.
Conclusion: Evidence is there that DNA could have evolved naturally.
I believe it has substantial evidence supporting it. The discovery of replicating protiens and primitive proto-viral organisms and scientists have been able to produce very primitive replicating proteins in the lab.
There is a world of difference beween any old "theory" and a scientific theory. Scientific theories have a lot of hoops to jump through before they become excepted.
What scientists?
Fewer doesn't equal none. It doesn't alter the fact that there is clear evidence of transitions in the fossil record.
It has been picked up, and tossed back.
If there is a "designer" - who designed the designer?