Genetics

Early in psychiatric genetic research, the field was drawn into the ‘nature versus nurture’ controversy in which the contribution of heritable factors was argued to be negligible to sufficient. This debate was fuelled by divergent conceptualizations of mental disorders as biological entities or psychological phenomena. A complex pattern of inheritance which did not obey simple Mendelian rules further added to the confusion about the role of genetics in psychiatry in the first half of the twentieth century. Two landmark papers discussed in this chapter (one by Seymour Kety and colleagues from 1968, the other by Robert Plomin and colleagues from 1994) were instrumental in establishing and contributing substantially to the study of genetics in mental disorders. The third paper by Irving Gottesman and James Shields (1967) clarified the polygenic nature of psychiatric disorders. Finally, the recent multinational collaborative efforts of the Psychiatric Genomics Consortium and Autism Sequencing Consortium (exemplified by papers from Ripke et al., 2014; Marshall et al., 2017; and Sanders et al., 2015) reveal the genetic architecture of common psychiatric conditions.