the comparison of perfectionism and related disorders among first, middle and late borns: rejection of sulloway's hypothesis

abstract aim and background: sulloway suggested that birth-order has a significant effect on personality traits, proposing first-borns children are more perfectionistic and more neurotic than later-borns. in abnormal form, perfectionism is closely associated with eating disorders and obsessive compulsive. the purpose of this study was to investigate the effect of birth-order on perfectionism, pathological eating attitude, obsessive compulsive features, and obsessive compulsive personality. methods and materials: this study was a post facto research. the statistical population of the research comprised of male and female undergraduate students in tabriz and sarab branches of payam e noor, and azarbayjan universities in the academic year 1390-91. a group of 790 university students, using stratified random sampling method, took part in this research. participants answered to the perfectionism inventory, eating attitude test (eat-26), obsessive compulsive inventory- revised (oci-r) & millons obsessive compulsive personality scale. data were analyzed using correlational coefficient and one way analysis of covariance. findings: there are no significant differences on perfectionism, pathological eating attitude, obsessive compulsive disorder, and obsessive compulsive personality among first, middle and late born. conclusions: sulloways theory and the effect of birth order on personality traits are not approved.