Yep. there is quite a bit of assumptions being made here (in my opinion) and I don't side with any particular idea. I prefer to try to gap both. Off course, from limited knowledge and unlimited ignorance. We can seat here all day and argue over DNA, but none of us (or at least most of us) are bio engineers here, so lets face it. We don't know for sure.
Just because we hear in the news that a new gene responsible for cancer has been found, it doesn't mean God is at fault. I am not defending God here, I am just pointing out the obvious. Whatever origin you believe on, the truth is that we've been on earth for a very very long time. Whomever designed us, is far separated from the current state of affairs. The question would be, as an organism, are we getting better (naturally speaking) or are we deteriorating as a result of the environment we created around us. Science is beginning to realize that DNA is not absolute. That the sole presence of a gene is not deterministic and that such gene has be allowed to express its information in order for that cancer to begin. That's most likely why no DNA test will ever "assure you" of your chances of getting cancer, they only give a percentage.
One thing I argue with JWs when it comes to the subject of "intelligent design" is their stand on the matter. Unless I misunderstood, they believe that Jehovah is in control of the universe always making sure everything is in the right place. Evolution is no-no because God created us at his image. My question would be... who is more powerful and wise? Someone who creates a machine that needs constant watching and adjusting, or someone who creates a machine that can manage and control itself? Does God need to be constantly adjusting and watching the universe? or would it make more sense to think that an all knowing all powerful God, created a universe and then set laws into place so that the universe will work by itself? In a nutshell, they seem to think that an appearance of God being able to do so much at once is a show of power, when in reality is the other way around. This is a perfect example of mankind trying to adjust their environment to fit their belief. No science is free of this problem. We all know that and many fence-seating JWs have come here to point that out. Difference is that science is no dogma.
Like someone else pointed, the universe if full of "Faults", but as a race we have learned that those faults have given way to the universe as we know it today. The human body is no exception. Wether those faults are causing us to live less, or they show that God does not exist, well you are free to conclude. What I think we can conclude for sure is that, wether God or evolution are the catalyst for the creation of man, the location of your butt-hole is not definite evidence of either one and neither is DNA.