I'm not sure I understand what point you were trying to make let alone agree with whatever point you think you're trying to make.
It seemed pretty straightforward.
If the natural and the artificial can look exactly alike, how do you tell the difference?
DNA seems to be the ultimate enigma.
For whom?
To suggest we can "assume" that a 'natural" origin of DNA somehow precludes "intelligent design" is simply empirically unsupportable.
I'm not assuming anything.
The origins of life are unknown.
I
expect the answer to be some natural process. I consider that
more likely. Sure.
There is exactly zero reason to expect something else.
If I had to choose where to invest a billion dollars for researching this, I'ld spend it on a team looking for a natural process, instead of a team looking for a god (oeps, sorry, "designer").
As for your claim that this expectation is empirically unsupportable - that's also ridiculous.
We have a gazibillion examples of natural chemical and bio-chemical processes producing all kinds of things (including many building blocks of life which were previously branded "too complex to form naturally" by a
certain group of people - you know who they are).
We have zero examples of "designers" capable of doing such a thing, if we don't count ourselves.
(edit: typo)