When a part of a person's body, their DNA, is taken to compare against a crime scene, it is done so only when sufficient burden of proof has been met
to justify the invasion of self and the invasion of privacy. It is part of an interrogation. Questioning, evaluation, and testing are all parts of
an interrogation. So by taking this DNA from innocent children they are subjecting them to interrogation, without knowledge or consent, every time a
computer compares their sequence to a sample. No court order, no warrant, not even probable cause. Just, "Johnny had trouble making friends when he
was five."
Since 2004 police have had the power to take DNA samples from anyone over the age of 10 who is arrested, regardless of whether they are later
charged, convicted, or found to be innocent.
I don't know about anyone else, but if I'm going to get screwed by the Government I'd at least like to leave the light on.