Behavior Genetics

, Volume 30, Issue 1, pp 51–58 | Cite as

Physical Similarity and Twin Resemblance for Eating Attitudes and Behaviors: A Test of the Equal Environments Assumption

  • Kelly L. Klump
  • Amanda Holly
  • William G. Iacono
  • Matt McGue
  • Laura E. Willson


The Equal Environments Assumption (EEA) in twin studies of eating pathology was investigated by examining the hypothesis that twin resemblance for eating attitudes and behaviors is affected by their degree of physical similarity. Eating attitudes and behaviors were assessed in 338 female adolescent twin pairs with a revised version of the Eating Disorder Inventory (EDI). General physical similarity as well as body size/shape similarity were assessed using ratings of color photographs, ratings of body shape, and body mass index. All physical similarity assessments were conducted blind to twin zygosity. Significant associations between physical similarity and twin similarity for eating attitudes and behaviors were not found. Mean EDI within-twin pair absolute difference scores did not differ significantly among more versus less physically-similar groups. Additionally, correlation and regression analyses failed to find a significant association between EDI absolute difference scores and physical similarity indices. The current findings provide support for the EEA in twin studies of eating attitudes and behaviors.

Equal environments assumption physical similarity twin study eating pathology adolescent 


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Copyright information

© Plenum Publishing Corporation 2000

Authors and Affiliations

  • Kelly L. Klump
    • 1
  • Amanda Holly
    • 2
  • William G. Iacono
    • 2
  • Matt McGue
    • 2
  • Laura E. Willson
    • 2
  1. 1.Department of PsychologyMichigan State UniversityEast Lansing
  2. 2.Department of PsychologyUniversity of MinnesotaMinneapolis

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