Let us talk first: what happens to soul after death. In my humble opinion, the immortal soul, a popular concept in theology, is the energy that makes us alive. Once that energy is gone, we are dead. The molecules including DNA (we will talk about DNA later), tissue, organs etc are there but no life. [I recall folk saying: chuk lo, chuk lo, hoe-ju-gee, jadd udgia bhaur (energy) vajudoon (body)]. What happens to this energy. This becomes part of universal energy according to the well-established scientific fact. This is law of thermodynamics as I have mentioned in the article above:
" The entire universe is energy. According to law of thermodynamics, this energy can neither be created nor be destroyed. Everything in the universe came from this 'Energy' and will go back to this 'Energy' (because energy can convert into matter and matter can convert into energy). 'Everything' means all matter including human beings and all other beings. [There is no place for details but I have detailed account including consciousness etc in my book that should be out sometime in 2006 "Science, Religion, and Spirituality"]
I am not interested in whether you are a scientist or not and agree or disagree, but please try to understand. If you do, it will clear the entire concept of immortal soul and soul merging with God, atma-parmatma etc. So coming back when this soul or energy is gone at the time of death, it merges with universal energy which we can call by any name: God, Parmatma, Universal energy, lord of the universe, or any other name you prefer.
So everybody's soul merges with God irrespective of our deeds. As we hear quite often from our brothers in theology.
So far nothing about DNA. Now how does DNA fits into this picture. Understanding role of DNA is very crucial when we talk about reincarnation of soul etc and karma theory. If you pay attention, the above soul/energy doesn't explain anything about reincarnation etc because that energy after death is not intact anymore. It was just for the functioning of that particular organized body. It has merged with universal soul and can be used for anything.
Believe whatever anyone wants depending on one's understanding: DNA is the only molecule that can be passed from one generation to other and carries all the genetic information. If there is no DNA there is no life the way we know it and nothing to pass on. So that's where DNA has its role if we believe in reincarnation of soul.
I know these concepts make many of us feel uncomfortable because it shatters all our myths. For them they are free to keep their myths, if they think that's the truth. I believe that only truth sets us free.