The current study used factor analysis to assess the degree to which personality characteristics derived from different theories signify the same latent personality constructs, and biometric modeling to understand the genetic and environmental structure of these constructs. Participants were drawn from the Twin and Offspring Study in Sweden…

Argues that an evolutionary perspective can unite the study of species-typical development and individual variation. Provides examples from the domains of personality, social, and intellectual development. Maintains that understanding the ways in which genes and environments work together helps developmentalists identify children who need…