Correlation between some personality test scores of siblings and intercorrelations between the scores

"No significant relationships were found between the personal adjustment scores of siblings or between their introversion-extraversion scores. Significant correlations were obtained between the intelligence test scores of siblings, these being .63 for high school students and .41 for college students." "The only significant intercorrelation between the test scores was obtained between the intelligence test and the socio-economic test." Even these are low.