Only one fact is certain about the future of genetic research: it will continue to raise ethical challenges for scientists, research participants, clinicians and patients (Faraone et al, 1999). Ethical issues are of concern in all branches of medicine and genetics, but they are of particular concern in the field of psychiatric genetics. This is because of the special nature of psychiatry, and its position at the intersection of the disciplines of psychology, sociology and medicine. The concern is also related to the perceived subject matter of psychiatry: the core thoughts, feelings and emotions by which we define ourselves as human beings. Many are perturbed by the idea that modifying genes could modify these features. By ‘interfering’ with our genetic heritage, it is perceived that our essential humanity is coming under threat, and the possible outcomes of this interference are worryingly unknown.