Sibling Differentiation in Adolescence: Implications for Behavioral Genetic Theory

Abstract

The presence of sibling "differentiating processes"--defined as processes in which increased sibling similarity in environmental or genetic factors leads to differences in sibling outcomes-poses a challenge for standard behavioral genetic theory and research. The presence of differentiation processes may affect estimates of genetic and environmental parameters in ways that have not been fully recognized. Utilizing data from the Nonshared Environment and Adolescent Development project, this study examined whether differentiating processes existed for seven composite indices of positive and negative adolescent adjustment. The 720 sibling pairs in the study were broken down into groups by age difference (0-4 years) between siblings. The hypothesis that siblings close in age would demonstrate lower correlations on adjustment measures was generally supported at two time points, three years apart. However, siblings one year apart at Time 1 were more similar to each other than were siblings two years apart, suggesting that shared environmental influences counteract sibling differentiation processes for these siblings. The overall trend supporting sibling differentiation was found to be unrelated to measures of sibling positivity and negativity.

Early and Middle Adolescents' Autonomy Development: Impact of Maternal HIV/AIDS

“…The Sigafoos et al (1988) measure is wellgrounded in theory, has shown high levels of internal consistency and consistent and significant correlations between each subscale and adolescent leadership experience, providing evidence for construct validity; and has been used in a number of research studies over the years (e.g. Feinberg & Hetherington, 2000;Keller et al, 2001;Simeon, Nixon, Milin, Jovanovic, & Walker, 2005;Wehmeyer, Kelchner, & Richards, 1996). However, it is based on parental report.…”

What makes siblings different? The development of sibling differences in academic achievement and interests.

“…Their question arose from the observation that, although they are 50% genetically similar, on average, and usually grow up in the same home, full biological siblings are typically no more similar to one another than they are to strangers. Indeed, accumulating evidence reveals that siblings often differ in domains ranging from substance use (Whiteman, Jensen, & Maggs, 2013) to anti-social behavior, depression, and general self-worth (Feinberg & Hetherington, 2000), and to academic interests and achievement (Conley, Pfeiffer, & Velez, 2007). Based on their analyses, Plomin and colleagues (Dunn & Plomin, 1991; Plomin, Manke, & Pike, 1996; Reiss et al, 1994) concluded that the major source of variation between siblings was not genetic differences but rather, their nonshared environments.…”

“…Given findings of the relatively high levels of heritability for intelligence and cognitive skills (Plomin & Spinath, 2004), and because of the centrality of schooling in youths’ lives, we targeted sibling differences in academic achievement and interests. Grounded in ideas of sibling social comparison and differentiation (Ansbacher & Ansbacher, 1956; Feinberg & Hetherington, 2000; Schachter & Stone, 1986) and drawing on expectancy value theory (Wigfield, & Eccles, 2000), we examined: (a) the role of parents’ beliefs about sibling differences in academic ability in the development of sibling differences in academic achievement; and (b) the role of sibling differences in academic achievement in the development of sibling differences in academic interests. Using three years of longitudinal data, we controlled for siblings’ prior average grades and interests in an effort to isolate the effects of parents’ beliefs about sibling differences and measured sibling differences on youth’s academic development.…”

Friend, foe, or both? A retrospective exploration of sibling relationships in elite youth sport

“…This is due to non-shared genes and differences in environment and parenting. Although behavioural geneticists have suggested that these differences between siblings may emerge, they may also arise through sibling deidentification processes (Ansbacher & Ansbacher, 1956;Feinberg & Hetherington, 2000).…”