title: Lower marriage and divorce rates among twins than among singletons in Danish birth cohorts 1940-1964.
abstract: Few studies have examined differences of civil status of twins and singletons and the conclusions are contradictory. In the present study, based on a linkage between the Danish Twin Register, a random 5% sample of the total Danish population, and administrative register databases, the authors compare rates of marriage and divorce in a sample of 35,975 twins and 81,803 singletons born 1940-1964. Cox-regressions are used in order to control for potential confounders. We find that compared with singletons twins have significantly lower marriage rates: (males: 15-19 years: Hazard Ratio (HR) = 0.66 (95%CI: 0.58-0.76); 20-24 years: 0.85 (0.82-0.88); 25 years or more: 0.96 (0.93-0.98) and females: 15-19 years: 0.70 (0.67-0.75); 20-24 years: 0.83 (0.80-0.85); 25 years or more: 0.94 (0.91-0.97)). There is no difference in divorce rates for males, but a significantly lower divorce rate for female twins compared with singletons (HR=0.87, 95%CI: 0.83-0.90). These differences offset each other, thus 57% of both populations remain in their first marriage until censoring. The interpretation may be that since twins have a partner from birth, they do not have the same need for marriage as singletons but have more experience in maintaining a relationship if they do marry.
authors.affiliation: The Danish Twin Registry, Epidemiology, University of Southern Denmark, Denmark. ipetersen@health.sdu.dk
authors.forename: Inge
authors.initials: I
authors.lastname: Petersen
authors.forename: Torben
authors.initials: T
authors.lastname: Martinussen
authors.forename: Matthew
authors.initials: M
authors.lastname: McGue
authors.forename: Paul
authors.initials: P
authors.lastname: Bingley
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
mesh_terms: D000328:Adult; D001723:Birth Rate; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D003718:Denmark / Q000453:epidemiology; D004243:Divorce / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008393:Marriage / Q000706:statistics & numerical data*; D008875:Middle Aged; D012307:Risk Factors; D013997:Time Factors; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*