Assume Nothing...

DNA is not self replicating.

DNA is certainly a key to understanding, in part, how life works. It is not by any means an accurate simplistic full story of the incredible complexity of life, even at the level of bacteria. The fact is that even DNA replication itself is a very complex process. It is certainly not a simple process of DNA replicating itself, as atheist reductionist scientists would like you to believe. DNA cannot be really understood in isolation. It is part of and dependent on some very complicated processes and molecular machinery.

Those who believe that science can explain life generally paint life's realities as being much much simpler than they really are. They cannot accept that that part of reality is very far beyond present science. They cannot recognize or will not admit that science is merely a tool with major limitations nor do they admit that life is so complex that it strongly points to the necessity of design and from that to the probable existence of a designer. Science does not prove this, but it also does not prove anything like a full explanation for life and DNA is only a small part of the reality of life. In fact, DNA replication itself requires multiple molecular machines. These machines require the pre-existence of DNA.

This is a major chicken and egg paradox.
While DNA is probably the primary information storage element in a very complex system, there is no proof even that it provides all the information needed for life. We only know that it provides needed information, especially to make proteins (via another set of molecular machines) but it has not been proven that it provides all the information required and there have been articles in science magazines which indicate the life is dependent on other information besides that contained in DNA.

DNA defines how proteins are made and also to some extent the functional relationships between the various biological systems which operate together to make life possible. DNA defines certain potentials in life but doe not provide the answers as to how all that potential came to be transferred to life nor how it came to work together in interactions so complex that the greatest inventions of man pale in comparison even to a bacteria.
The fact that we know the structure of DNA and to a significant extent the role of DNA in making proteins does not mean we even begin to understand life, let alone how life came into existence. Science cannot begin to explain how the first DNA of any form came into existence. DNA alone cannot replicate itself either and science is also at a loss to explain the origin of all the molecular machines.

DNA not only does not self replicate and it is only an information template which is used by the molecular chemical machines to make more DNA and RNA. DNA can only be replicated by a sequential and very complex set of chemical processes which require about half a dozen at least of very complex chemical machines (enzymes) operating together in many properly coordinated ways. The following figure is a very simplistic representation of a small part of the replication process and shows three molecular machines at work in replicating DNA.

It is very important to understand that without proteins, DNA could not be made and without DNA, proteins can't be made. Without DNA and quite a number of molecular machines (made from proteins), life of any type we know of could not exist. This has profound implications for the limits of Darwinian evolution and scientific reductionism to explain the origin and the incredible biosphere and evolution of almost countless life forms.

Without the necessary enzymes, DNA cannot be even replicated even if it came into existence by extremely low chance occurrences to begin with. Life requires many types of molecules to exist for life to sustain itself and such molecules can only be made by life. In other words, for the molecules which life needs to be formed, life must first exist. (Again, this is the chicken and egg circular process with no proven scientific explanation as to how either could come into existence to begin with.) The circular relationship of protein manufacturer also is true for DNA replication itself. DNA replication requires molecular machines which are made from the information at least mostly contained in DNA.

There are some totally unproven theories about how DNA might have originated, but they have at best only a very low probability of being a real explanation and no significant laboratory evidence exists of such a process exists. Even if those theories were true, how did the replication machinery needed to replicate the DNA come into existence without DNA? There are also repair mechanisms (machines) needed to keep the DNA from mutating itself out of existence. (Yes, mutation does occur. There is just no significant proof of it producing changes above simple and nearly continuous at the molecular level.)

Science knows of no proven way for DNA replication to occur without these special enzymes which move along the DNA, unzipping the DNA as the enzyme molecule moves from base to base. DNA replication also requires enzymes by which nucleotides move in to each strand of the unzipped DNA. The bases of these nucleotides are in part, of course, located by molecular forces which determine what they connect to. The new bases are arranged in the new DNA to duplicate the opposite strand which has been separated.
When the enzyme moving along and unzipping the DNA gets to the end of the DNA, two nearly identical DNA molecules remain. Each contains one side of the original DNA and one side made of "new" nucleotides. Due to molecular (thermal and quantum) noise, however, mistakes are made in the process. This is where the repair machines are required. Occasionally a base pair in one DNA molecule doesn't match the corresponding base in the other molecule. It is estimated that about one mistake is made in every billion base pairs. That's the same as typing out a dictionary several times and getting a wrong letter at most one time! It is hard to believe such a near perfect process happened to arise by some inanimate process by chance.
In order to get the error rate that low, there are proofreading molecular machines (made from the pattern contained in the DNA which somehow know what the DNA code should be! (By chance survival selection??????)) The error correcting molecular machines move along the DNA correcting almost all mistakes! Without error correction molecular machinery, life of any complexity could not continue to exist.

Life would self destruct as errors quickly accumulated. This is another part of the chicken and egg problem for which science has no explanation.

This is a process of incredible complexity just to replicate DNA. It points out the magnitude of science ignorance as to trying to explain how DNA originated in the first place if one rejects a designer. If evolution were the answer, all the enzymes had to evolve also before or at the same time with each enzyme somehow being reproduced and being more survivable at each step. One would have to, in all candor, ask; how did such complex chemical machines evolve independently at each step without DNA and wind up with functions thereafter so perfect to replicate DNA with such precision. Stated simply, without DNA to use as a template, what was the function of such enzymes without anything to replicate? How were the enzymes replicated before they made DNA?

Even if you once had DNA, then you have to have molecular machines (coded by the DNA) to be in existence for the proteins needed by life and to replicate the molecular machines themselves to come into existence. Without those proteins, no life, and without life no DNA and without DNA no proteins. If all these science findings seem to be going in circles, that is a correct impression. Science cannot really explain life at a deep level.

Again, DNA replication is not simple. DNA does not replicate itself. DNA replication is, rather, probably the ultimate chicken and egg problem that leaves science with no real answer and very little if any probability of ever coming up with an answer. If anyone tells you DNA explains all of life, they are trying to sell you a rotten egg which had no material chicken to bring it into existence in the first place.

DNA itself like so much of life's elements, seems to require a Designer or at least a design process.
Science in many other ways also points to the need for a designer in life, a designer of the laws of physics, and a designer who set the conditions at the beginning of the universe which makes life even possible as we know it. The mysteries of DNA origin and replication are one of the pointers to design. Draw your own conclusions about the Designer.
DNA does not explain all of life.