Twin relationships in old age: A developmental perspective

The relationship development of 133 monozygotic (MZ) and 60 same-sex dizygotic (DZ) older twin pairs was studied retrospectively and contrasted with their other sibling relationships. Results indicate: (i) Since adolescence, MZ twins lived closer to one another and had more frequent contact, social support, and emotional closeness. For both MZ and DZ pairs, contact and emotional closeness decreased since early adulthood, but increased again in old age. Dyadic differences in these variables were highly stable over time. (ii) Compared with their other sibling relationships, the relationships between MZ and DZ twins were more intense with respect to all relationship domains (e.g., contact, intimacy, conflict, and support). (iii) Whereas higher attachment security and relationship satisfaction in MZ pairs were independent of contact frequency, security and satisfaction were less intense in DZ pairs and strongly dependent on their contact. It is concluded that MZ and DZ twin relationships are different kinds of sibling relationships in old age.