Direct marital assortment for cognitive and personality variables

Recent advances in linear modeling in human genetics permit the resolution of the sources of assortative mating. Using these methods we examined the multivariate assortment relationships among education, general cognitive ability, and personality traits in two large samples of spouses from the Colorado Adoption Project (N=334 couples) and the Hawaii Family Study of Cognition (N=1165 couples). Results indicate a direct pairing of mates on the basis of eductional level and general intelligence but no cross-assortment between the two. Thus, the indirect marital correlation between education in one spouse and intelligence in the other is due only to the direct pairing on education and on intelligence and to the within-person correlation between the two traits. We also found direct isomorphic assortment as well as direct cross-assortment on some personality characteristics. However, there was no cross-assortment between the personality and the cognitive domains. Results from models based on conditional path assortment parameters differ markedly from those obtained directly from observed marital correlations.This research was supported in part by Grants HD-10333, HD-18426, and HD-19802 from the National Institute of Child Health and Human Development (NICHD), by Grants BNS-7826204 and BNS-8200310 from the National Science Foundation, and by a grant from the Spencer Foundation. The paper was written while Kay Phillips and Craig Nagoshi were supported by training Grants HD-07289 from the NICHD and DA-07043 from the National Institute on Drug Abuse, respectively. Preparation of the paper was facilitated by Grant RR-07013-20 awarded to the University of Colorado by the Biomedical Research Support Grant Program, Division of Research Resources, National Institutes of Health.