But they will.
Life is an inevitable outcome of the fundamental symmetries of the universe.
Because - when we're talking about DNA, one must realize that it's NOT the sequence that's being selected for, it's the shape of the resulting protein.
The question "what are all the DNA sequences that can create this shape" is a different question from "what is the probability of creating this sequence".
There is not just one way to create life, there are many. Ours happens to be left handed, all the biomolecules are l isomers - why? Who knows. There's no reason it has to be this way. At some point something evolved left handed and then everything else had to follow suit. Or maybe there was a more abundant supply of left handed source material. Or something.
Here's what happens in real life - there are 14 different ways a strand of RNA can wind around a ribosome. The same exact pair of molecules, can assume 14 different stable configurations, and in each case the winding will be different. You can have monomers, dimers, trimers, and 4-mers, all form naturally and spontaneously in water whenever the components are mixed.
Mathematically, you have one large molecule interacting with another, on the basis of shape, charge, and geometric flexibility. If you'd like a mind blower, read up on the self assembly of microtubules, and then ask yourself how they stay in one place. Vesicular transport is another good one, as is muscle contraction.
The point being, it is not sufficient to look at something and claim it's a species. Modern identification techniques involve things like the 16S rRNA sequence to identify and catalog species. People discussing this topic should be familiar with the basic mutation types.
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