And then imagine
That the sample at the scene was degraded and they had to use LCN DNA and it pointed to you even though it wasnt you ergo the Omagh bombing case
Just before the attack you kissed her/him on the cheek and the recovered DNA was from your salivia, thats you sharing soap with big bubba for 25 years, after all thats your DNA in an intimate place.
What you dont realise is that the DNA at the scene isnt useless, the oft quoted Sally Bowman case was solved because a sample taken lawfully following an arrest some time later produced a match to the crime scene.
I will wager two things, one you havent voluntarily provided a life time sample to the police and, secondly, that you believe CSI Vegas, Miami, Grimsby et al are reflective of modern UK policing!
If your so adamant the system works pop down your local nick and volunteer your DNA, just remember when you do, DNA at crime scenes carries no real time stamp so you better hope you havent shed a hair,skin or anything else somewhere that ends up a crime scene!