Genetic and environmental influences on thin‐ideal internalization

Abstract

Objective Current research on the etiology of thin-ideal internalization focuses on psychosocial influences (e.g., media exposure). The possibility that genetic influences also account for variance in thin-ideal internalization has never been directly examined. This study used a twin design to estimate genetic effects on thin-ideal internalization and examine if environmental influences are primarily shared or nonshared in origin. Method Participants were 343 post-pubertal female twins (ages 12–22; M=17.61) from the Michigan State University Twin Registry. Thin-ideal internalization was assessed using the Sociocultural Attitudes toward Appearance Questionniare-3. Results Twin modeling suggested significant additive genetic and nonshared environmental influences on thin-ideal internalization. Shared environmental influences were small and non-significant. Discussion Although prior research focused on psychosocial factors, genetic influences on thin-ideal internalization were significant and moderate in magnitude. Research is needed to investigate possible interplay between genetic and nonshared environmental factors in the development of thin-ideal internalization.

Mediators of the relationship between thin-ideal internalization and body dissatisfaction in the natural environment

“…Furthermore, results indicated that momentary thin-ideal importance was associated with momentary body dissatisfaction, above and beyond the influence of simply thinking about appearance, providing further justification for the existence of a state-based component of internalization. These findings thus challenge the notion that thin-ideal internalization is a static construct (e.g., Colautti et al, 2011; Suisman et al, 2012). Rather and in line with Karazsia et al (2013), it appears that thin-ideal internalization can be at least somewhat activated or downplayed in the moment, likely due to contextual factors (e.g., attention paid to thin-ideal stimuli; Brown & Dittmar, 2005), which should be explored further in future studies.…”

“…Thin-ideal internalization has generally been described as “trait-like” in the literature (e.g., Colautti et al, 2011; Suisman et al, 2012), but we found there was moment-to-moment variability in individuals’ reports of one aspect of this construct, thin-ideal importance. Furthermore, results indicated that momentary thin-ideal importance was associated with momentary body dissatisfaction, above and beyond the influence of simply thinking about appearance, providing further justification for the existence of a state-based component of internalization.…”

“…We hypothesized that momentary engagement in body, eating, and exercise social comparisons and body surveillance would mediate the relation between trait thin-ideal internalization and momentary body dissatisfaction. Given that thin-ideal internalization has typically been conceptualized as “trait-like” in the literature (e.g., Colautti et al, 2011; Suisman et al, 2012), we were interested in how the hypothesized mediation model would hold when thin-ideal internalization was assessed at the trait level. However, we were also interested in testing this assumption (i.e., that thin-ideal internalization is a stable, trait-like construct), as some work has argued for state-like components for this construct and that it can be influenced by contextual factors (Karazsia, van Dulmen, Wong, & Crowther, 2013).…”

Socialization and selection effects in the association between weight conscious peer groups and thin-ideal internalization: A co-twin control study

“…If genetic selection effects play a role, this could be via heritable personality traits, such as perfectionism, which have been hypothesized to contribute to genetic risk for thin-ideal internalization (Suisman et al, 2012). Indeed, these same traits may also contribute to peer group selection (i.e., girls similar in personality may be more likely to form friendships with one another).…”

“…Given significant associations between BMI and thin-ideal internalization (Suisman et al, 2012, 2014), as well as evidence for clustering of BMI among friend groups (Fletcher et al, 2011), BMI was used as a covariate in all analyses. BMI was calculated ([weight])/[height] 2 ) from measures of height and weight made using a wall-mounted ruler or tape measure and digital scale, respectively.…”