Undue influence of weight on self-evaluation: a population-based twin study of gender differences.
OBJECTIVE
To explore the extent to which genetic and environmental factors contribute to liability to placing undue importance on weight as an indicator of self-evaluation and to determine whether differences exist across genders in the nature and magnitude of these effects.


METHODS
Self-report data were collected on 8,045 same-sex and opposite-sex twins, aged 18-31 years, from a population-based registry of Norwegian twins. Structural equation modeling was utilized to estimate the relative contribution of genetic and environmental factors to liability for undue influence of weight on self-evaluation, allowing for gender-specific effects.


RESULTS
Individual variation in undue influence of weight on self-evaluation was best explained by shared and individual environmental influences. No significant gender differences were found. Shared environmental factors accounted for 31% of the variance.


CONCLUSIONS
These results raise the possibility that there may be distinct sources of familial resemblance for different symptoms of bulimia nervosa as codified in the 4th ed. of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1994).
Reichborn-Kjennerud
Ted
T
Division of Epidemiology, The Norwegian Institute of Public Health, Oslo, Norway. ted.reichborn-kjennerud@fhi.no
Bulik
Cynthia M
CM
Kendler
Kenneth S
KS
Roysamb
Espen
E
Tambs
Kristian
K
Torgersen
Svenn
S
Harris
Jennifer R
JR
D000293:Adolescent; D000328:Adult; D000856:Anorexia Nervosa / Q000175:diagnosis / Q000235:genetics*; D001835:Body Weight; D002032:Bulimia / Q000175:diagnosis / Q000235:genetics*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011159:Population Surveillance; D012042:Registries; D012649:Self Concept; D011795:Surveys and Questionnaires; D014427:Twins / Q000235:genetics* / Q000523:psychology