... developing the disorder. Holland et. al's twin study also provided a lot of proof that genetics do play a part in the development of eating disorders - his study was based on the theory that monozygotic twins (who share identical genetic makeups) would have a higher chance of both members of the pair developing anorexia nervosa than dizygotic twins (who have genetically non-identical DNA). His findings were that out of the 34 twin pairs (and one set of triplets), 56% of the 16 monozygotic twins were concordant for anorexia (both members of the pair had the disorder),and 7% of the dizygotic pairs were concordant. Thus there is a high indication that there can be a genetic vulnerability to anorexia nervosa, in spite of the experimental validity of Holland's research being questioned (the independent variable, genetic relatedness, was not able to be manipulated by the experimenter as it occurred naturally, thus ...

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