Badcock and Crespi have advanced the hypothesis that autism and schizophrenia are caused by imbalanced imprinting in the brain. They argue that an imbalance between the effects of paternally and maternally expressed genes on brain development results in either an extreme paternal (autism) or maternal brain (schizophrenia). In this paper their conceptual model is discussed and criticized since it presupposes an incoherent distinction between observable physical and hidden mental phenomena. An alternative model is discussed that may be more fruitful for (...) investigating the possible role of imprinted genes in the development of social behaviour. The development of crying and reactive crying and behaviours necessary for collaborative action are discussed as a promising research area for understanding the effects of imprinted genes. (shrink)