Sharing DNA with a Criminal Cousin

Former Policeman, Plaid Gwersyllt, on the Plaid Wrecsam blog  notes that North Wales Police is rather slow in implementing the European Court ruling that the DNA of innocents should be removed from the police databases.

The campaign to remove "innocent" DNA is one that confuses me.  My understanding, which is limited, is that my fingerprints are absolutely unique. You can't look at my fingerprints and say Ah! That proves that he is his father's son or his son's father! But that this isn't true of DNA.

Although my DNA is unique I share some of it with my family, and it is possible to do a paternity test to prove that my sprogs are mine and not the milkman's by using DNA.

As far as I know North Wales police don't have any of my DNA. A genealogical service does hold it; I paid them to take a sample so they could see how I am related to others who have paid them to compare samples. They regularly e-mail me to say that "Jo Blogs probably shares a paternal ancestor with you" etc.

Jeffrey Gafoor was convicted of the murder of Lynette White, because the police had the DNA of his cousin's convicted son, and that was sufficient to narrow the suspect range to members of the Gafoor family.

Even if all innocent people's absolute personal DNA is removed from the database, won't the DNA that the innocent share with the guilty still be on the database?

Even if I am as pure as the driven snow, but I have a criminal father, grandfather, uncle, son, grandson, nephew, second cousin twice removed etc, then won't my shared DNA still be on file, despite my personal innocence?

If this is the case isn't the argument about innocents' DNA a bit futile?