Endophenotypes for Marital Status in the NAS-NRC Twin Registry

Abstract

This study explored two possible endophenotypes for marital status: 1) the predisposition to form and maintain lasting pair bonds and 2) the predisposition to have multiple mates over the life span. These endophenotypes were constructed using 1972 and 1985 marital status data from a followed-up subsample of the NAS-NRC WWII Veteran Twin Registry. In the 1972 data, consisting of 2297 MZ and 2443 DZ twin pairs, 42% of the variance in pair bonding could be attributed to additive genetic and 58% to nonshared environmental factors and measurement error. Of the variance in multiple mates, 28% could be attributed to additive genetic and 62% to nonshared environment/error factors. In the 1985 data, consisting of 1359 MZ and 1208 DZ twin pairs, 31% of the variance in pair bonding could be attributed to non-additive genetic and 69% to nonshared environment/error factors. Of the variance in multiple mates, 22% could be attributed to additive genetic and 78% to nonshared environment/error factors. Although parameter estimates were marked by wide confidence intervals, no variance in either endophenotype could be attributed to common family environment.