title: Twin studies of eating disorders: a review.
abstract: OBJECTIVE
  Twin methodology has been used to delineate etiological factors in many medical disorders and behavioral traits including eating disorders. Although twin studies are powerful tools, their methodology can be arcane and their implications easily misinterpreted.
  
  
  METHODS
  The goals of this study are to (a) review the theoretical rationale for twin studies; (b) provide a framework for their interpretation and evaluation; (c) review extant twin studies on eating disorders; and (d) explore the implications for understanding etiological issues in eating disorders.
  
  
  CONCLUSIONS
  On the basis of this review, it is not possible to draw firm conclusions regarding the precise contribution of genetic and environmental factors to anorexia nervosa. Twin studies confirm that bulimia nervosa is familial and reveal significant contributions of additive genetic effects and of unique environmental factors in liability to bulimia nervosa. The magnitude of the contribution of shared environment is less clear, but in the studies with the greatest statistical power, it appears to be less prominent than additive genetic factors.
authors.affiliation: Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Medical College of Virginia of Virginia Commonwealth University, Richmond, VA 23298-0126, USA. cbulik@hsc.vcu.edu
authors.forename: C M
authors.initials: CM
authors.lastname: Bulik
authors.forename: P F
authors.initials: PF
authors.lastname: Sullivan
authors.forename: T D
authors.initials: TD
authors.lastname: Wade
authors.forename: K S
authors.initials: KS
authors.lastname: Kendler
mesh_terms: D000856:Anorexia Nervosa / Q000235:genetics* / Q000523:psychology; D002032:Bulimia / Q000235:genetics* / Q000523:psychology; D004200:Diseases in Twins / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D012307:Risk Factors; D012931:Social Environment; D018433:Twin Studies as Topic