Contrary to one possible interpretation of my title, this paper will not advocate any scepticism or ontological deflation. My concern will rather be with how we should best think about a realm of phenomena the existence of which is in no doubt, what has traditionally been referred to as the genetic. I have no intention of questioning a very well established scientific consensus on this domain. It involves the chemical DNA, which resides in almost all our cells, which is capable of producing copies of itself that accurately reproduce a very long sequence of components, and which plays a role in the physiology of the cell which in certain basic respects is quite well understood. This substance has also achieved a remarkable iconic status in contemporary culture. It is seen as fundamental to personal identity both in the practical sense of providing a criterion of identity through DNA testing, and in the much deeper sense of being seen as, somehow, defining who we are. The latter role is illustrated, for example, by the recent debate about the right of children conceived by sperm donation to know who are their fathers. Such people, it is passionately argued, must be able to find out where they came from, who they really are. On a daily basis we are confronted with claims about the discovery of the genetic basis of—or in fact very often the ‘gene for’—all manner of psychological and physical characteristics, and all kinds of disorders. This holds out apparent possibilities