Department of Psychology, Georgia State University.
Department of Psychology, Purdue University.
Dev Psychol. 2014 Mar;50(3):663-73. doi: 10.1037/a0034345. Epub 2013 Sep 9.
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.
青春期和成年早期是同伴群体对年轻人生活的影响越来越大的时期。接触偏差同伴的年轻人容易受到外化行为和相关精神病理学的影响。除了与偏差同伴联系的环境相关性之外，越来越多的证据表明，与偏差同伴的联系是遗传的。本研究使用纵向双胞胎研究设计，考察了遗传和环境因素对与偏差同伴联系的影响程度、这些因素相对重要性的变化，以及这些因素中哪些因素有助于在这一关键发育时期保持联系的稳定性。该研究评估了同性别双胞胎（485 对同卵双胞胎，271 对异卵双胞胎）在 3 个不同年龄：15、18 和 21 岁时的联系。生物计量模型显示，遗传影响随着年龄的增长而增加。新的遗传影响出现在青春期后期，到 21 岁时没有新的遗传影响出现。双胞胎之间共享的环境影响随着年龄的增长而减少，而每个个体特有的非共享环境效应的比例在整个发展过程中相对稳定。共享环境影响主要是年龄重叠的，而非共享环境影响主要是年龄特定的。总之，本研究发现，与偏差同伴的联系的变化可以通过共享和非共享环境影响以及遗传影响来解释（到 21 岁时占 46%），这支持了遗传影响的选择因素的作用。共享环境几乎完全负责青春期后期的稳定性，而遗传影响主要负责成年早期的稳定性。
