Abstract
Genetic variation influencing normal and abnormal human behaviour has been studied since Francis Galton's work in the second half of the 19th century. However, most of these studies have consisted of biometric analysis of complex phenotypes; the genotype has been treated as a 'black box'. The concepts and analytical tools of modern genetics have rarely been used. In this lecture, some examples are given of approaches combining tools from genetics, cytogenetics, and various fields of neurobiology which might help in the analysis of genetic mechanisms leading, in interaction with the environment, to individual differences in behaviour, mental performance, and susceptibility to mental diseases.