A TEST OF HARRIS,J.R. THEORY OF PEER INFLUENCES ON PERSONALITY

J. R. Harris's (1995) theory that peer influence plays a central role in shaping personality was tested from the data of the National Merit twin study (J. C. Loehlin & R. C. Nichols, 1976), by examining whether members of 839 late-adolescent twin pairs who shared more friends wer e more similar in personality than those who shared fewer friends. Amb iguity regarding the direction of effects was partially controlled by comparing monozygotic and dizygotic twin pairs. Comparisons were made between the effect of peer overlap and similarity of parental treatmen t. These were made both for personality traits, as measured by the Cal ifornia Psychological Inventory, and for academic achievement, as meas ured by the subscale and total scores of the National Merit Scholarshi p Qualifying Test. A number of the results were consistent with Harris 's theory, although quantitatively the effects were not strong.