Examines the interplay between genes and environment and argues that the development of much individual variation can be explained in terms of relatively simple forms of underlying regulation. Looks at "sensitive periods," during which variation is produced by experience received at a particular age. Includes a discussion of the…

This special issue of the "Courrier," a journal for professionals concerned with issues related to the physical and psychological development of children, provides (1) an overview of 25 years of internationally coordinated research, (2) a selection of papers published by the research teams, and (3) a description of the teams and their…