Aims: To establish whether there is any genetic basis for the eating disorder Anorexia Nervosa (AN)
Procedure: 34 pairs of twins were studied in a clinical session to establish how many of the individuals suffered suffered from AN.
Findings: A concordance rate of 55% for MZ twins was reported, compared to a rate of 7% for DZ twins.
Conclusion: AN is strongly influenced by genetic factors, although since the concordance was not 100%, there must be other influences as well.
Strength: The fact that the concordance was not 100% provides hope to sufferers that their condition isn't an inescapable result of their biological makeup.
Weakness 1:The sample was very small, and the results may not generalize.
Weakness 2: It may be that factors other than genes are influencing these results; for example identical twins are likely to be treated differently from non-identical twins, and this may contribute to behavioural abnormalities.