Genetic Similarity Shared by Best Friends Among Adolescents

Guang Guo
2006 Twin Research and Human Genetics  
T wo observations suggest a genetic similarity among close friends: (1) the observed similarity among friends in certain traits and behaviors; (2) the evidence that many of these traits and behaviors have a genetic component. This hypothesis is tested using monozygotic (MZ) twins, dizygotic (DZ) twins, full biological siblings, and their best friends from the National Longitudinal Study of Adolescent Health (Add Health). Whether the resemblance between MZ twins' friends is larger than that
more » ... rger than that between friends of DZ twins and full siblings is investigated with respect to 4 individual traits or behaviors: grade point average (GPA), AHPVT (the version Peabody Picture Vocabulary Test [PPVT] designed for Add Health), aggressive behavior, and depression. Our hypothesis is supported in analyses among same-sex friends (not among different-sex friends) for GPA, aggressive behavior, and AHPVT. Similarity Among Friends It has long been recognized that friends or peers tend to hold similar attitudes, exhibit similar attributes, or engage in similar behaviors. Berelson et al. (1954) found that individuals with best friends who are Democrats are more likely to vote for Democratic presidential candidates than individuals with Republican friends. Duncan et al. (1972) reported that students whose friends have college plans are more likely to have college plans themselves controlling for
doi:10.1375/183242706776402920 pmid:16611476 fatcat:4rfzm7zkcvck3eh77nnj5x6acu