Abstract
The relationship development of 133 monozygotic (MZ) and
60 same-sex dizygotic (DZ) older twin pairs was studied ret-
rospectively and contrasted with their other sibling relation-
ships. 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 adult-
hood, 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 con-
cluded that MZ and DZ twin relationships are different kinds
of sibling relationships in old age.
