Genetic factor analysis for twins and non-twins: An application to Yatabe-Guilford personality inventory data

A genetic factor model for analyzing twin and non-twin data simultaneously, which is one of the structural equation model, is examined in a study of Yatabe-Guilford (Y-G) personality inventory. The sample analyzed by this method includes 187 monozygotic (MZ) twin pairs, 43 dizygotic (DZ) twin pairs and 1309 non-twins. Non-twin data can be used for stabilizing factor covariance structure. Genetic influences, common environment, and non-shared environment account for 2.5%, 32.5%, and 65.0% of the variance in the factor of adaptability, respectively. They account for 49.8%, 10.3% ,and 39.9% of the variance in the factor of extroversion, respectively. The genetic factor analysis finds evidence of a greater environmental contribution to variance in adaptability than in extroversion.