The national DNA Database of England & Wales is the largest forensic DNA database in the world. Since 1995 it has quickly developed to hold the genetic profiles of over two million people. This collection of tissue samples, taken without consent from a sizeable collection of the population, has engendered a number of ethical commentaries on its legitimacy as a proportionate response to crime. This paper examines the ways in which the ethical discourses, which surround the uses of the National DNA Database, drew upon and deployed a number of distinct representations of DNA. It is argued that key ideas about DNA have become central to everyday assertions about the benefits and dangers of this forensic technology.