Gilbert Gottlieb was an elegant experimentalist whose research was inspired in part by naturalistic observations of parent-offspring vocal-auditory interactions of waterfowl. Such observations are essential in identifying potential linear (obvious) as well as nonlinear (subtle) mechanisms underlying the development of species-typical behavior. His…

Described is an ongoing study of monozygotic and dizygotic twins, separated in infancy and reared apart. Discussed are the procedures and results of this study with interpretations of the results. The effects of parenting, education, and other interventions are considered. (CW)