Spouse similarity in American and Swedish couples.

A very similar pattern of homogamy was found in samples of American and Swedish couples for physical, social, and behavioral variables. In the Swedish sample, there were only minor differences in assortment, i.e., in similarity to spouses, between MZ and DZ twins. Although our data are not conclusive on this point, there was an indication that the observed similarity of spouses for most variables is due to initial assortment rather than to convergence of phenotypes after initial contact. Exceptions are that spouses do appear to converge for highly plastic variables such as alcohol consumption and amount of social activity.