My own view is that the process is ultimately based on divine guidance via
"chance" movement of atoms and molecules, natural selection acting on
mutations, etc. The entire universe is set up and run just so as to
"naturally" bring about almost of the events necessary for God's plan to
happen, e.g., in the case of a gene, having just the right star explode at
just the right time to send a cosmic ray to the exact point in a certain
organism's DNA to cause the right mutation.
>(In passing, I would like to know why the original gene is not
>mutated whereas the copy is. If they are copies of each other shouldn't they
>be equally subject to mutation?)
>
Either the original or the copy could mutate, but if both mutated the
organism might be in trouble. If the position of the gene relative to
something else affected its function, then only those organisms in which
the copy mutated but the original remained normally functioning would do
well.