ABSTRACT
The general notion that genes might in uence behavior has proved surprisingly controversial (Rutter, 2006a). Some of the concerns expressed have focused on methodological issues in relation to behavior genetics, some on the excessive claims of some genetic evangelists, some on a supposedly implied biological determinism, some on the problems in studying genetic in uences on socially de ned behaviors, and some on the negative messages about the possibility of making preventive or therapeutic interventions effective. However, many psychosocial researchers have been quite reluctant to accept the reality of genetic effects on individual differences, and some have seemed to want to place developmental psychology outside of both biology and medicine. This wish to separate off psychology is, however, based on a misunderstanding of what is entailed in a biomedical approach. Accordingly, it is necessary to outline some of the main biomedical principles before turning to the speci cs of genetic concepts and ndings. This is essential because any adequate understanding of the processes of normal and abnormal development must be based on these principles.
