Birth Order, Sex of Subject and Sex of Sibling as Factors in Extraversion and Neuroticism in Two-Child Families

Abstract
Using the Eysenck Personality Inventory, Extraversion and Neuroticism scores were obtained for 120 college students from two-child families. When the effects of birth order and sex of S were examined, a significant interaction occurred for Extraversion, with firstborn males and second-born females reporting higher scores. Higher Neuroticism scores occurred for Ss with opposite-sexed siblings than for those with the same-sexed sibling. Results suggest that Extraversion and Neuroticism are influenced by position in the two-child family.