Perhaps it was there from the beginning, but served the purpose of only starting the whole process but is NOT the process in of itself.
Well, in the case of DNA, this formation is pretty much dictated by the mathematics of hydrocarbon chemistry - including the spiral, the double chain, and so on. Just like benzene, but a larger and more complicated organic molecule.
Not at all the same thing as a kid building something randomly out of tinkertoys - the atomic rules themselves dictate what molecules can form and which are not possible.