Genetic and Environmental Influences on Affiliation With Deviant Peers During Adolescence and Early Adulthood

• Published in: Developmental psychology 2014-03, Vol.50 (3), p.663-673
• Main Authors: Tarantino, Nicholas, Tully, Erin C, Garcia, Sarah E, South, Susan, Iacono, William G, McGue, Matt
• Format: Article
• Language: English
• Subjects: Adolescence; Adolescent; Adolescent Behavior; Adolescents; Adult and adolescent clinical studies; Adulthood; Adults; Age Factors; Antisocial Behavior; Behavior Problems; Biological and medical sciences; Biomimetics; Child development; Correlation; Correlation analysis; Developmental psychology; Developmental Stages; Environment; Environmental aspects; Environmental Effects; Environmental Influences; Female; Fundamental and applied biological sciences. Psychology; Gene-Environment Interaction; Genes; Genetic factors; Genetics; Human; Human genetics; Humans; Late Adolescents; Longitudinal Studies; Male; Medical sciences; Minnesota; Peer Group; Peer Groups; Peers; Personality Development; Personality Inventory; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychopathology; Psychopathology. Psychiatry; Risk; Risk Factors; Risk theory; Role; Siblings; Social Behavior Disorders - etiology; Social Behavior Disorders - genetics; Social behavior disorders. Criminal behavior. Delinquency; Statistics as Topic; Twins; Young Adult; Young Adults; Young people
• ISSN: 0012-1649; 1939-0599
• DOI: 10.1037/a0034345

Adolescence and early adulthood is a time when peer groups become increasingly influential in the lives of young people. Youths exposed to deviant peers risk susceptibility to externalizing behaviors and related psychopathology. In addition to environmental correlates of deviant peer affiliation, a growing body of evidence has suggested that affiliation with deviant peers is heritable. This study examined the magnitude of genetic and environmental influences on affiliation with deviant peers, changes in the relative importance of these factors, and which of these factors contribute to the stability of affiliation across this critical developmental period using a longitudinal twin study design that assessed same-sex twins (485 monozygotic pairs, 271 dizygotic pairs) at 3 discrete ages: 15, 18, and 21 years of age. Biometric models revealed that genetic influences increased with age. New genetic influences appeared during late adolescence, and no new genetic influences emerged by age 21. Environmental influences shared by sibling pairs decreased with age, while the proportion of nonshared environmental effects unique to each individual remained relatively stable over the course of development. Shared environmental influences were largely age-overlapping, whereas nonshared environmental influences were largely age-specific. In summary, this study found variance in affiliation with deviant peers is explained by shared and nonshared environment effects as well as by genetic influences (46% by age 21), supporting the role of genetically influenced selection factors. The shared environment was almost exclusively responsible for the stability in late adolescence, while genetic influences were primarily responsible for stability in early adulthood.