MCTFR Summaries of Research Publication Findings



Abstracts from Research Publications (chronological)

Billig, J.P., Hershberger, S.L., Iacono, W.G., & McGue, M. (1996). Life events and personality in late adolescence: Genetic and environmental relations. Behavior Genetics, 26, 543-554.

  • The relationship between life events and personality was investigated in the Minnesota Twin/Family Study, using 216 monozygotic and 114 dizygotic 17-year-old male twin pairs. Participants completed a life events interview designed for adolescents and the Multidimensional Personality Questionnaire. Life events were categorized into three types: life events to which all members of a family would be subject and those affecting an individual, which can be broadly construed as either nonindependent or independent. Univariate genetic model fitting indicated the presence of significant genetic effects (h 2=49%) for nonindependent nonfamily life events but not for the other two types of life events. Bivariate genetic model fitting further confirmed that the significant phenotypic correlation between nonindependent life events and personality is in part genetically mediated. Specifically, the findings suggest that genetically influenced individual differences in constraint play a substantial role in life events whose occurrence is not independent of the individual's behavior.

McGue, M., Slutske, W., Taylor, J., & Iacono, W.G. (1997). Personality and substance use disorders. I. Effects of gender and alcoholism subtype. Alcoholism: Clinical & Experimental Research, 21, 513-520.

  • The relationship between alcoholism and self-rated personality was explored in a community-ascertained sample of 303 male and 103 female alcoholics, and 304 male and 770 female nonalcoholics. Alcoholics met DSM-III-R lifetime criteria for alcohol dependence; personality was assessed using the Multidimensional Personality Questionnaire. Compared with controls, alcoholics scored significantly higher on all indicators of negative emotionality, and consistently lower on all indicators of constraint. Individual effect sizes were moderate in both the male and female samples. A subsample of severe male alcoholics, identified by cluster analysis, was characterized by relatively early onset of problem drinking and relatively high antisociality and familial loading of problem drinking; they were also more extreme than moderate male alcoholics on negative emotionality and constraint. When taken in aggregate, personality risk appears to be associated with a continuum of alcoholic risk such that individuals extreme in both negative emotionality and behavioral disinhibition have especially high rates of alcoholism.

Hur, Y.M., McGue, M., & Iacono, W.G. (1998). The structure of self-concept in female pre-adolescent twins: A behavioral genetic approach. Journal of Personality and Social Psychology, 74, 1069-1077.

  • Two hundred and forty-three female monozygotic (MZ) and 164 female dizygotic (DZ) twin pairs, aged 11 and 12 years, who participated in the ongoing Minnesota Twin Family Study, completed six specific scales of the Piers-Harris Children's Self-Concept Scale (P-H). Model-fitting analyses yielded three major conclusions. First, approximately 30% of the variance in specific self-concepts in female preadolescents was due to genetic factors, with the remaining variance being accounted for primarily by nonshared environmental factors and measurement error. Second, the underlying common genetic, shared environmental, and nonshared environmental factors influenced specific facets of self-concept directly and independently, rather than through an intervening phenotypic general self-concept. Finally, whereas genetic, shared environmental, and nonshared environmental factors were necessary to explain the commonality among the specific self-concept scales, only genetic and nonshared environmental factors were sufficient to explain the specificity of those scales.

McGue, M., Slutske, W., & Iacono, W.G. (1999). Personality and substance use disorders. II. Alcoholism versus drug use disorders. Journal of Consulting and Clinical Psychology, 67, 394-404.

  • The relationship between personality and substance use disorders was investigated in a community-based sample of 638 individuals who were alcoholic and/or had a drug use disorder, and 1,530 individuals who did not have a substance use disorder. Personality was assessed by the Multidimensional Personality Questionnaire; substance use diagnoses were based on standard criteria as assessed by interview. Data were analyzed using a 3-factor (Gender x Alcoholism x Drug Use Disorder) multivariate analysis of variance. The significant alcoholism main effect was associated primarily with negative emotionality, whereas the significant drug use disorder main effect was associated primarily with constraint. No significant interactions with gender were observed. These findings suggest that the elevated levels of behavioral disinhibition observed with alcoholic individuals may be attributable to a subset of alcoholic individuals who also abuse drugs other than alcohol.

Taylor, J., McGue, M., Iacono, W.G., & Lykken, D.T. (2000). A behavioral genetic analysis of the relationship between the socialization scale and self-reported delinquency. Journal of Personality, 68, 29-50.

  • This investigation examined the genetic (A), and shared (C) and nonshared (E) environmental variance contributions to the relationship of self-reported delinquency (as measured by the "Delinquent Behavior Inventory" [DBI; Gibson, 1967]) to the Socialization (So) scale of the California Psychological Inventory using univariate and bivariate structural equation models. The scales were administered to 222 male (145 monozygotic; 77 dizygotic) and 159 female (107 monozygotic; 52 dizygotic) 16- to 18-year-old same-sex twin pairs. Principal components analysis with varimax rotation revealed three interpretable So factors representing family/home environment, self-concept, and behavioral control. Univariate modeling suggested sex differences in etiological influences associated with individual differences in most scales. The bivariate ACE model fit the data, suggesting that the covariance between the So scale and self-reported delinquency owes in part to shared etiological factors.

Krueger, R.F., McGue, M., & Iacono, W.G. (2001). The higher order structure of common DSM mental disorders: Internalization, externalization, and their connections to personality. Personality and Individual Differences, 30, 1245-1259.

  • Comorbidity among mental disorders is commonly observed in clinical and epidemiological samples. Can comorbidity be understood as meaningful covariance, and is this covariance structure linked with personality We addressed this question in a sample of 634 female and 549 male, middle-aged participants in the Minnesota Twin-Family Study (MTFS). Mental disorders were assessed using the Structured Clinical Interview for DSM-III-R. the Substance Abuse Module front the Composite International Diagnostic Interview, and a specially-designed interview for the assessment of antisocial personality disorder. Personality was assessed using the Multidimensional Personality Questionnaire. Relations among symptom scales for eight common DSM disorders were compatible with hypothesized underlying bivariate normal distributions. Polychoric correlations among these scales were well-fit by a two-factor model positing internalizing and externalizing factors, which, in turn, were correlated with broad personality dimensions. Internalizing was positively correlated with negative emotionality (and negatively with positive emotionality in women) and externalizing was negatively correlated with constraint. These findings suggest that internalization, externalization, and their links to personality may provide a useful framework for understanding covariance among common adult mental disorders.

Burt, S.A., McGue, M., Iacono, W., Comings, D., & MacMurray, J. (2002). An examination of the association between DRD4 and DRD2 polymorphisms and personality traits. Personality & Individual Differences, 33, 849-859

  • To date, evidence supporting a positive association between the 7-repeat allele of the D4 dopamine receptor (DRD4) exon III 48 bp polymorphism and Novelty Seeking (NS) has been mixed, with some studies confirming and others refuting the association. A positive association between NS and the minor Taq1 A allele (A1) of the D2 dopamine receptor (DRD2) has also been reported. In the present study, we sought to replicate the associations between the DRD4 and DRD2 polymorphisms and various personality traits, as measured by the Multidimensional Personality Questionnaire. The sample consisted of 137 families (n=348) assessed as part of the ongoing Minnesota Twin Family Study. The data were analyzed at both the individual-level, to maximize comparability with previous studies, and at the family-level, to control for population stratification. The DRD4 and DRD2 polymorphisms were not associated with MPQ measures related to NS, results that may cast doubt on the generalizability of previous positive findings.

Johnson, W., Krueger, R. F., Bouchard, T.J., & McGue, M. (2002) The Personalities of Twins: Just Ordinary Folks. Twin Research, 5, 125-131.

  • Twin studies have demonstrated that personality traits show moderate genetic influence. The conclusions drawn from twin studies rely on the assumptions that twins are representative of the population at large and that monozygotic and dizygotic twins are comparable in every way that might have bearing on the traits being studied. To evaluate these assumptions, we used Multidimensional Personality Questionnaire (MPQ) data from three samples drawn from the Minnesota Twin Registry (totaling 12,971 respondents) to examine the effect sizes associated with mean differences on the 11 MPQ scales and 3 higher-order MPQ factors for singletons versus twins and MZ twins versus DZ twins. The singletons in the samples were family members of the participating twins. We also used ratios of scale variances to examine the significance of variance differences. The only mean or variance difference replicated across all three samples was greater Social Closeness (about.1 standard deviation) for twins than for singletons. This difference was obtained for both males and females. It would appear that, with respect to personality, twins are not systematically different from other people. Our results also highlight the importance of replication in psychological research because each of our large samples showed differences not replicated in other samples.

Klump, K.L., McGue, M., & Iacono, W.G. (2002). Genetic relationships between personality and eating attitudes and behaviors. Journal of Abnormal Psychology, 111, 380-389.

  • Genetic and environmental factors underlying relationships between personality traits and disordered eating were examined in 256 female adolescent twin pairs (166 monozygotic, 90 dizygotic). Eating behaviors were assessed with the Total Score, Body Dissatisfaction, Weight Preoccupation, Binge Eating, and Compensatory Behavior subscales from the Minnesota Eating Disorders Inventory (M-EDI; K. L. Klump, M. McGue, & W. G. Iacono, 2000). Personality characteristics were assessed with the Negative Emotionality, Positive Emotionality, and Constraint scales from the Multidimensional Personality Questionnaire (MPQ; A. Tellegen, 1982). Model-fitting analyses indicated that although genetic factors were more likely to contribute to MPQ and M-EDI phenotypic associations than environmental factors, shared genetic variance between the 2 phenotypes was limited. MPQ personality characteristics may represent only some of several genetic risk factors for eating pathology.

Krueger, R.F., Hicks, B.M., Patrick, C.J., Carlson, S.R., Iacono, W.G., & McGue, M. (2002). Etiologic connections among substance dependence, antisocial behavior, and personality: Modeling the externalizing spectrum. Journal of Abnormal Psychology, 111, 411-424.

  • A hierarchical biometric model is presented of the origins of comorbidity among substance dependence, antisocial behavior, and a disinhibited personality style. The model posits a spectrum of personality and psychopathology, united by an externalizing factor linked to each phenotype within the spectrum, as well as specific factors that account for distinctions among phenotypes within the spectrum. This model fit self-report and mother-report data from 1,048 male and female 17-year-old twins. The variance of the externalizing factor was mostly genetic, but both genetic and environmental factors accounted for distinctions among phenotypes within the spectrum. These results reconcile evidence for general and specific causal factors within the externalizing spectrum and offer the externalizing factor as a novel target for future research.

Elkins, I.J., McGue, M., Malone, S., & Iacono, W.G. (2004). The effect of parental alcohol and drug disorders on adolescent personality. American Journal of Psychiatry, 161, 670-676.

  • Objective: The relationship of parental alcohol or drug diagnosis to offspring personality was examined in a population-based sample of 17-year-old twins (568 girls and 479 boys) participating in the Minnesota Twin Family Study. Whether offspring personality characteristics 1) are specific to the type of substance use disorder in parents (alcohol versus drug) and 2) are found in high-risk offspring without substance use disorders as well as in offspring with substance use disorders was investigated. Method: Personality was assessed with the Multidimensional Personality Questionnaire; substance use disorders were assessed in person through diagnostic interviews. Results: In both male and female offspring, parental history of alcohol dependence was associated with greater negative emotionality, aggression, stress reaction, and alienation but lower wellbeing; parental history of drug disorders was associated with lower constraint, control, harm avoidance, and traditionalism but higher social potency. Excluding offspring with a substance use disorder had virtually no effect on the statistical significance of these findings. Conclusions: In contrast to findings in some adult samples, personality characteristics associated with a family history of substance use disorders are found even in adolescent offspring who have not yet developed these disorders themselves, suggesting that personality might be one indicator of familial risk for substance use disorders during this developmental stage. Personality profiles of offspring of parents with substance use disorders also show some diagnostic specificity, with constraint associated with parental drug abuse and negative emotionality with parental alcoholism.

Benning, S.D., Patrick, C.J., Blonigen, D.M., Hicks, B.M., & Iacono, W.G. (2005). Estimating facets of psychopathy from normal personality traits: A step toward community-epidemiological investigations. Assessment, 12, 3-18. PMCID: PMC2242356

  • In three samples consisting of community and undergraduate men and women and incarcerated men, we examined the criterion validity of two distinct factors of psychopathy embodied in the Psychopathic Personality Inventory (PPI) as indexed by primary trait scales from the Multidimensional Personality Questionnaire (MPQ). Consistent with the PPI factors themselves, MPQ-estimated PPI-I related negatively with internalizing disorder symptoms and fearfulness and positively with thrill and adventure seeking, sociability, activity, and narcissism. MPQ-estimated PPI-II was associated negatively with socialization and positively with externalizing disorder symptoms, impulsivity, disinhibition and boredom susceptibility, and trait anxiety and negative emotionality. Additionally, PPI-I was selectively related to the interpersonal facet of Factor 1 of the Psychopathy Checklist—Revised (PCL-R), whereas PPI-II was related preferentially to Factor 2 of the PCL-R.

Benning, S.D., Patrick, C.J. & Iacono, W.G. (2005). Psychopathy, startle blink modulation, and electrodermal activity in twin men. Psychophysiology, 42, 753-762.

  • Psychopathy is a personality disorder with interpersonal–emotional and antisocial deviance facets. This study investigated these facets of psychopathy prospectively using normal-range personality traits in a community sample of young adult men who completed a picture-viewing task that included startle blink and skin conductance measures, like tasks used to study psychopathy in incarcerated men. Consistent with prior research, scores on the interpersonal–emotional facet of psychopathy (“fearless dominance”) were associated with deficient fear-potentiated startle. Conversely, scores on the social deviance facet of psychopathy (“impulsive antisociality”) were associated with smaller overall skin conductance magnitudes. Participants high in fearless dominance also exhibited deficient skin conductance magnitudes specifically to aversive pictures. Findings encourage further investigation of psychopathy and its etiology in community samples.

Perkins, P.S., Klump, K.L., Iacono, W.G., & McGue, M. (2005). Personality traits in women with anorexia nervosa: Evidence for a treatment-seeking bias? International Journal of Eating Disorders, 37, 32-37.

  • OBJECTIVE: Several personality traits have been associated with anorexia nervosa (AN) in treatment-seeking samples of patients. The current study used a population-based sample to compare the personality characteristics of women with AN who sought treatment versus those who did not. METHOD: Participants included 27 (14 treatment-seekers, 13 non-treatment-seekers) women with threshold or subthreshold AN and 273 (64 treatment seekers, 209 non-treatment seekers) comparison women from the Minnesota Twin Family Study. Personality was assessed with the higher-order factors and primary scales of the Multidimensional Personality Questionnaire (MPQ). RESULTS: Non-treatment-seeking women showed lower levels of negative emotionality, stress reaction, and alienation than treatment-seeking women. DISCUSSION: These results suggest that personality deviations may be overestimated in treatment-seeking samples.

Blonigen, D.M., Hicks, B.M., Krueger, R.F., Patrick, C.J. & Iacono, W.G. (2006). Continuity and change in psychopathic traits as measured via normal-range personality: A longitudinal-biometric study. Journal of Abnormal Psychology, 115, 85-95. PMCID: PMC2242626

  • The discriminant validity of the interpersonal-affective and social deviance traits of psychopathy has been well documented. However, few studies have explored whether these traits follow distinct or comparable developmental paths. The present study used the Multidimensional Personality Questionnaire (A. Tellegen, in press) to examine the development of the psychopathic traits of Fearless Dominance (i.e., interpersonal-affective) and Impulsive Antisociality (i.e., social deviance) from late adolescence to early adulthood in a longitudinal-epidemiological sample of male and female twins. Results from mean- and individual-level analyses revealed stability in Fearless Dominance from late adolescence to early adulthood, whereas Impulsive Antisociality declined over this developmental period. In addition, biometric findings indicated greater genetic contributions to stability in these traits and greater nonshared environmental contributions to their change over time. Collectively, these findings suggest distinct developmental trends for psychopathic traits from late adolescence to early adulthood.

Cukrowicz, K.C., Taylor, J., Schatschneider, C. & Iacono, W.G. (2006). Personality differences in children with attention-deficit/hyperactivity disorder, conduct disorder and controls. Journal of Child Psychology and Psychiatry, 47, 151-159.

  • Background:  Differences in personality profiles were examined between children who differed in their co-morbidity of externalizing disorders: attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD). Methods:  11- and 17-year-old male and female twins from a community sample were categorized as ADHD only, CD only, co-morbid CD-ADHD, and controls (no ADHD or CD) based on threshold and subthreshold CD and ADHD diagnoses assessed with structured interviews. Multivariate analyses were used to identify patterns of personality that differentiate these four diagnostic groups. It was hypothesized that significant differences would be found in the pattern of personality variables between participants in the co-morbid group, compared to the other three groups, and that these differences would hold across developmental periods. Results:  As expected, the co-morbid group had a pattern of personality marked by higher Negative Emotionality and lower Constraint than the other diagnostic groups. This pattern was evidenced across gender and age cohort. Conclusions:  An extreme personality profile may represent a liability toward the occurrence of ADHD and CD with more extreme profiles contributing to the occurrence of both disorders among boys and girls. Implications for treatment planning and theoretical development are discussed.

Elkins, I.J., King, S.M., McGue, M. & Iacono, W.G. (2006) Personality traits and the development of nicotine, alcohol, and illicit drug disorders: Prospective links from adolescence to young adulthood. Journal of Abnormal Psychology, 115, 26-39.

  • The personality traits constraint (CN) and negative emotionality (NE) have been more (CN) or less (NE) consistently associated with alcoholism. The authors examined the association of personality at age 17 with timing of onset and with prospective prediction of nicotine, alcohol, and illicit drug disorders 3 years later in a twin sample (569 females; 432 males). Earlier onset of alcohol and drug disorders (by age 17) was related to significantly lower CN compared with later onsets (by age 20); high NE was related to either onset. NE, as well as CN, uniquely predicted new onsets of all 3 types of substance use disorders by follow-up, with preexisting substance disorders taken into account. Personality traits confer generalized risk for developing any substance disorder, though some traits are more strongly linked with some substance disorders than with others.

Elkins, I.J., King, S.M., McGue, M. & Iacono, W.G. (2006) Personality Traits and the Development of Nicotine, Alcohol, and Illicit Drug Disorders: Prospective Links from Adolescence to Young Adulthood. Journal of Abnormal Psychology, 115, 26-39.


Johnson, W., Hicks, B.M., McGue, M., & Iacono, W.G. (2007). Most of the girls are alright but some aren't: Personality trajectory groups from ages 14 to 24 and some associations with outcomes. Journal of Personality and Social Psychology: Personality Processes and Individual Differences, 93, 266-284.

  • Personality traits show normative patterns of development toward maturity during adolescence. Yet individuals follow these normative patterns to differing degrees. This study used growth mixture modeling to characterize personality development patterns and their associations with outcomes in a population-based sample of 1,537 girls aged 14 to 24. The authors used latent class analysis to identify 3 trajectory groups labeled alright (47%), growing up (42%), and trouble (11%). Alright group members were more likely at age 24 to have completed college, remained involved with their families, and obtained good jobs. Trouble group members were more likely to be involved with drugs and alcohol, to display interpersonal problems, and to behave antisocially. Growing up group members fell in between.

Blonigen, D.M., Carlson, M.D., Hicks, B.M., Krueger, R.F., & Iacono, W.G. (2008). Stability and change in normal personality traits from late adolescence to early adulthood: A longitudinal twin study. Journal of Personality, 76, 229-266. PMCID: PMC2586875

  • We conducted a longitudinal-biometric study examining stability and change in personality from ages 17 to 24 in a community sample of male and female twins. Using Tellegen's (in press) Multidimensional Personality Questionnaire (MPQ), facets of Negative Emotionality (NEM) declined substantially at the mean and individual levels, whereas facets of Constraint (CON) increased over time. Furthermore, individuals in late adolescence who were lowest on NEM and highest on CON remained the most stable over time, whereas those exhibiting the inverse profile (higher NEM, lower CON) changed the most in a direction towards growth and maturity. Analyses of gender differences yielded greater mean-level increases over time for women as compared to men on facets of CON and greater mean-level increases for men than women on facets of Agentic Positive Emotionality (PEM). Biometric analyses revealed rank-order stability in personality to be largely genetic, with rank-order change mediated by both the nonshared environment (and error) as well as genes. Findings correspond with prior evidence of a normative trend toward growth and maturity in personality during emerging adulthood.

Hicks, B.M., Johnson, W., Iacono, W.G., & McGue, M. (2008). Moderating effects of personality on the genetic and environmental influences of school grades helps to explain sex differences in scholastic achievement. European Journal of Personality, 22(3): 247-268. PMCID: PMC2836730

  • Girls consistently achieve higher grades than boys despite scoring lower on major standardized tests and not having higher IQs. Sex differences in non-cognitive variables such as personality might help to account for sex differences in grades. Utilizing a large sample of 17 year-old twins participating in the Minnesota Twin Family Study (MTFS), we examined the roles of Achievement Striving, Self-Control, and Aggression on sex differences in grade point average (GPA). Each personality trait was a significant predictor of GPA, with sex differences in Aggression accounting for one-half the sex difference in GPA and genetic variance accounting for most of the overlap between personality and GPA. Achievement Striving and Self-Control moderated the genetic and environmental influences on GPA. Specifically, for girls but not boys, higher Achievement Striving and Self-Control were associated with less variability in GPA and greater genetic and environmental overlap with GPA. For girls, certain personality traits operate to shape a context yielding uniformly higher GPA, a process that seems absent in boys.

Krueger, R.F., South, S., Johnson, W., & Iacono, W.G. (2008). The heritability of personality is not always 50%: Gene-environment interactions and correlations between personality and parenting. Journal of Personality, 76(6), 1486-1522. PMCID: PMC2593100

  • Twin studies of personality are consistent in attributing approximately half of the variance in personality to genetic effects, with the remaining variance attributed to environments that make people within the same families different. Such conclusions, however, are based on quantitative models of human individual differences that estimate genetic and environmental contributions as constants for entire populations. Recent advances in statistical modeling allow for the possibility of estimating genetic and environmental contributions contingent on other variables, allowing the quantification of phenomena that have traditionally been characterized as gene-environment interaction and correlation. We applied these newer models to understand how adolescents' descriptions of their relationships with their parents might change or moderate the impact of genetic and environmental factors on personality. We documented notable moderation in the domains of positive and negative emotionality, with parental relationships acting both to enhance and diminish both genetic and environmental effects. We discuss how genetic and environmental contributions to personality might be more richly conceptualized as dynamic systems of gene-environment interplay--systems that are not captured by classical concepts, such as the overall heritability of personality.

South, S.C., Krueger, R.F., Johnson, W., & Iacono, W.G. (2008). Adolescent personality moderates genetic and environmental influences on relationships with parents. Journal of Personality and Social Psychology, 94, 899-912. PMCID: PMC2603027

  • In contrast with early theories of socialization that emphasized the role of parents in shaping their children's personalities, recent empirical evidence suggests an evocative relationship between adolescent personality traits and the quality of the parent-adolescent relationship. Research using behavior genetic methods suggests that the association between personality and parenting is genetically mediated, such that the genetic effects on adolescent personality traits overlap with the genetic effects on parenting behavior. In the current study, the authors examined whether the etiology of this relationship might change depending on the adolescent's personality. Biometrical moderation models were used to test for gene- environment interaction and correlation between personality traits and measures of conflict, regard, and involvement with parents in a sample of 2,452 adolescents (M age = 17.79 years). They found significant moderation of both positive and negative qualities of the parent-adolescent relationship, such that the genetic and environmental variance in relationship quality varied as functions of the adolescent's levels of personality. These findings support the importance of adolescent personality in the development of the quality of the parent-adolescent relationship.

Tackett, J.L., Krueger, R.F., Iacono, W.G., & McGue, M. (2008). Personality in middle childhood: A hierarchical structure and longitudinal connections with personality in late adolescence. Journal of Research in Personality, 42, 1456-1462. PMCID: PMC2593456

  • Research on the structure of personality in middle childhood, while advancing, is still in the early stages of development. In this study, we employed a group of 1563 twins to elucidate the hierarchical structure of personality in middle childhood and provide connections to established personality traits in adult populations. Our results provide evidence for a higher-order structure of personality in middle childhood that maps on to recent findings in adult populations supporting hierarchical relationships among 2-, 3-, 4-, and 5-factor models of personality. In addition, primary higher-order personality traits rated by parents at age 11 showed substantial predictive validity for analogous traits rated by self at age 17. We discuss our results within the context of developing a convergent hierarchical taxonomy of personality in middle childhood and the importance of multiinformant investigations.

Bornovalova, M.A., Hicks, B.M., Iacono, W.G., & McGue, M. (2009). Stability, change, and heritability of borderline personality disorder traits from adolescence to adulthood: A longitudinal twin study. Development and Psychopathology, 21(2009), 1335-1353. PMCID: PMC2789483

  • Although personality disorders are best understood in the context of lifetime development, there is a paucity of work examining their longitudinal trajectory. An understanding of the expected course and the genetic and environmental contributions to these disorders is necessary for a detailed understanding of risk processes that lead to their manifestation. The current study examined the longitudinal course and heritability of borderline personality disorder (BPD) over a period of 10 years starting in adolescence (age 14) and ending in adulthood (age 24). In doing so, we built on existing research by using a large community sample of adolescent female twins, a sensitive dimensional measure of BPD traits, an extended follow-up period, and a longitudinal twin design that allowed us to investigate the heritability of BPD traits at four discrete ages spanning midadolescence to early adulthood. Results indicated that mean-level BPD traits significantly decline from adolescence to adulthood, but rank order stability remained high. BPD traits were moderately heritable at all ages, with a slight trend for increased heritability from age 14 to age 24. A genetically informed latent growth curve model indicated that both the stability and change of BPD traits are highly influenced by genetic factors and modestly by nonshared environmental factors. Our results indicate that as is the case for other personality dimensions, trait BPD declines as individuals mature from adolescence to adulthood, and that this process is influenced in part by the same genetic factors that influence BPD trait stability.

Eaton, N.R, Krueger, R.F., Johnson, W., McGue, M., & Iacono, W.G. (2009). Parental monitoring, personality, and delinquency: Further support for a reconceptualization of monitoring. Journal of Research in Personality, 43(2009), 49-59. PMCID: PMC2682426

  • Stattin and Kerr [Stattin, H., & Kerr, M. (2000). Parental monitoring: A reinterpretation. Child Development, 71(4), 1072–1085] suggested reconceptualizing “parental monitoring” and presented evidence from a Swedish sample that challenged current operational definitions. We replicate and extend their findings. Parental knowledge (“monitoring”) related more strongly to child disclosure than to parental solicitation of information in a more ethnically-diverse U.S. sample. We then addressed whether adolescents’ personalities accounted for the links between child disclosure, parental knowledge, and delinquency. Solicitation, knowledge, and disclosure generally did not predict delinquency when controlling for adolescent personality. Personality contributed significant incremental validity to the statistical prediction of delinquency above and beyond solicitation, knowledge, and disclosure; the reverse was generally not true. Adolescents’ personalities largely account for the “parental monitoring”-delinquency association, which supports reconceptualizing monitoring.


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