Genetic and Environmental Influences on Personality Trait Stability andGrowth During the Transition to Adulthood:A Three-Wave Longitudinal StudyChristopher J. Hopwood and M. Brent DonnellanMichigan State UniversityDaniel M. BlonigenVeterans Affairs Palo Alto Health Care System and StanfordUniversity School of MedicineRobert F. Krueger, Matt McGue, andWilliam G. IaconoUniversity of MinnesotaS. Alexandra BurtMichigan State UniversityDuring the transition to adulthood individuals typically settle into adult roles in love and work. Thistransition also involves significant changes in personality traits that are generally in the direction ofgreater maturity and increased stability. Competing hypotheses have been offered to account for thesepersonality changes: The intrinsic maturation hypothesis suggests that change trajectories are endoge-nous, whereas the life-course hypothesis suggests that these changes occur because of transactions withthe social environment. This study investigated the patterns and origins of personality trait changes fromages 17 to 29 using 3 waves of Multidimensional Personality Questionnaire data provided by twins.Results suggest that (a) trait changes were more profound in the first relative to the second half of thetransition to adulthood; (b) traits tend to become more stable during the second half of this transition, withall the traits yielding retest correlations between .74 and .78; (c) Negative Affectivity declined over time,and Constraint increased over time; minimal change was observed on agentic or communal aspects ofPositive Emotionality; and (d) both genetic and nonshared environmental factors accounted for person-ality changes. Overall, these genetically informed results support a life-course perspective on personalitydevelopment during the transition to adulthood.Keywords: transition to adulthood, personality development, behavior genetics, personality traitsThe transition to adulthood between the ages of 18 and 30involves significant psychological development with regard tointimacy, identity, work, and parenthood (see Arnett, 2000, 2007).These changes are also accompanied by both stability and changein personality traits (e.g., Blonigen, Carlson, Hicks, Krueger, &Iacono, 2008; Donnellan, Conger, & Burzette, 2007; Roberts,Caspi, & Moffitt, 2001; Robins, Fraley, Roberts, & Trzesniewski,2001). However, debates exist regarding whether exogenous orendogenous factors are more responsible for personality develop-ment during this period of the life span (Costa & McCrae, 2006;Roberts, Walton, & Viechtbauer, 2006b). Accordingly, the goal ofthis study was to evaluate genetic and environmental influences onpersonality stability and change during the transition to adulthoodusing three waves of personality trait data. Specifically, we exam-ined the etiological influences on stability and change in the higherorder personality traits of the Multidimensional Personality Ques-tionnaire (MPQ; Tellegen & Waller, 2008) using a sample of twinsassessed in late adolescence (approximately age 17), emergingadulthood (approximately age 24), and young adulthood (approx-imately age 29).Characterizing the Transition to AdulthoodSociologists (Furstenberg, Kennedy, McLoyd, Rumbaut, & Set-tersten, 2004; Shanahan, 2000), demographers (Rindfuss, 1991),and psychologists (Arnett, 2000, 2007) have identified severalthemes that characterize the transition to adulthood. First, thistransition takes time as individuals negotiate aspects of identitydevelopment and gradually assume adult roles and responsibilities(Arnett, 2004). In light of this fact, Arnett (2000) has proposed thatthe period of development from the late teens through the end ofthe 20s is a time of emerging adulthood. Indeed, he described theperiod of the early 20s as the “volitional years of life” (Arnett,2000, p. 469) because individuals seem to spend considerableresources exploring issues of identity and intimacy. Second, onaverage, more demographic transitions occur during the yearsbetween 18 and 30 than any others in the life course (Rindfuss,1991). Thus, by the age of around 30, most individuals haveThis article was published Online First January 17, 2011.Christopher J. Hopwood, M. Brent Donnellan, and S. Alexandra Burt,Department of Psychology, Michigan State University; Daniel M. Blonigen,Veterans Affairs Palo Alto Health Care System, Palo Alto, California, andDepartment of Psychiatry and Behavioral Science, Stanford University Schoolof Medicine; Robert F. Krueger, Matt McGue, and William G. Iacono, De-partment of Psychology, University of Minnesota.This research was supported by National Institutes of Health Grants R01DA05147 (to William G. Iacono) and R01 AA09367 (to Matt McGue).Correspondence concerning this article should be addressed to Christo-pher J. Hopwood, 107A Psychology, Michigan State University, EastLansing, MI 48824-1116. E-mail: [email protected] of Personality and Social Psychology © 2011 American Psychological Association2011, Vol. 100, No. 3, 545–556 0022-3514/11/$12.00 DOI: 10.1037/a0022409545assumed at least one of the major roles of adulthood, and thereforethe 30s seem to mark the beginning of adulthood proper. Third,there appears to be a considerable amount of variability amongindividuals in terms of the sequencing of the life transitions be-tween adolescence and adulthood (Rindfuss, 1991).The salient developmental challenges and diversity of experi-ences people encounter in this phase of the life course suggest thatthe transition to adulthood represents an important period forresearch on personality development. Existing research suggeststhat many of the psychological changes that occur during thisperiod tend to be in the direction of increased psychologicalmaturity (Caspi, Roberts, & Shiner, 2005). Indicators of psycho-logical well-being such as self-esteem appear to increase (Donnel-lan, Trzesniewski, & Robins, 2006; Galambos, Barker, & Krahn,2006), whereas attributes such as depression, anger, and external-izing problems appear to decline (Arnett, 2000, 2007; Galambos etal., 2006). Consistent with these trends, personality trait change isgenerally positive: Traits become more stable in general (Roberts& DelVecchio, 2000), and individuals tend to decline in NegativeAffectivity and show increases in behavioral constraint during thetransition to adulthood (Blonigen et al., 2008; Donnellan et al.,2007; Roberts et al., 2001). Moreover, young adulthood appears tobe the time in