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Keywords:

  • thin-ideal;
  • internalization;
  • body image;
  • disordered eating;
  • twin study;
  • heritability;
  • Tripartite Model

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 postpubertal female twins (ages: 12–22 years; M = 17.61) from the Michigan State University Twin Registry. Thin-ideal internalization was assessed using the Sociocultural Attitudes toward Appearance Questionnaire-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. © 2012 by Wiley Periodicals, Inc. (Int J Eat Disord 2012)