DNA carries a person's identity. It also carries a vast amount of other information about that person's biology, health and, increasingly, psychological predispositions. This information could have great medical value, en masse, but might be abused, ad hominem, by insurers, employers, politicians and civil servants. Some countries are building up DNA databases, initially using the excuse that these are for the identification and prosecution of criminals, but also including the unprosecuted and the acquitted. Should such databases be made universal? Is it ever right for the DNA of the innocent to be used for any purpose without the consent of the "owner". If so, when?