This chapter shows the ways in which narratives of psychiatric genetics employ a variety of invocations of complexity to present psychiatric genetics research as a cautious, flexible and responsible science. Psychiatric genetics provides a case study of the defence of a controversial science: in this case, narratives drawing on complexity account for past failures and neutralize criticisms of genetic determinism by incorporating both the unknown and ‘non-genetic’ factors within their theoretical models. Recombinant DNA techniques and advances in chromosomal mapping allowed researchers to construct genetic linkage maps to identify the relative positions of mutations. A common element of the narrative of psychiatric genetics is the emergence of complexity in accounting for past failures, justifying ‘delays’ in gene discovery, and justifying new methods. The chapter identifies two temporal strategies through which a narrative of psychiatric genetics is organized: retrospective accounting and prospective accounting.