Background. There were four purposes of the current study, including the investigation of the: (i) adequacy of a multidimensional measure of body image; (ii) genetic and environmental epidemiology of this measure; (iii) shared variance between genetic and environmental risk factors for body mass index (BMI) and body image; and (iv) Equal Environment Assumption (EEA) as it related to body attitudes.

Method. Six types of body attitudes, as measured by the Body Attitudes Questionnaire (BAQ) and reported by 894 complete female–female twin pairs (mean age 32·35 years, S.D.=41·8) from the Australian Twin Registry, were analysed.

Results. Confirmatory factor analysis of the BAQ supported the adequacy of the measure. Additive genetic and unique environmental influences best accounted for the variance of all six of the BAQ subscales. The relationship between BMI and body attitudes was primarily due to shared genes rather than environment but the majority of genetic and environmental effects on body attitudes were independent of BMI, with the exception of the Feeling Fat subscale, which shared 53% of its genetic risk factors with BMI. One violation of the EEA was suggested, namely similarity of childhood treatment influenced similarity on Lower Body Fatness subscale.

Conclusions. Findings support the notion that: (i) body image is a multidimensional concept; (ii) it is relatively independent of BMI; and (iii) both genetic and non-shared environment are influential determinants of body attitudes.