Lower marriage and divorce rates among twins than among singletons in Danish birth cohorts 1940-1964

TY - JOUR

T1 - Lower marriage and divorce rates among twins than among singletons in Danish birth cohorts 1940-1964

AU - Petersen, Inge

AU - Martinussen, Torben

AU - McGue, Matthew

AU - Bingley, Paul

AU - Christensen, Kaare

PY - 2011/4

Y1 - 2011/4

N2 - 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.

AB - 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.

U2 - 10.1375/twin.14.2.150

DO - 10.1375/twin.14.2.150

M3 - Journal article

C2 - 21425897

SN - 1832-4274

VL - 14

SP - 150

EP - 157

JO - Twin Research and Human Genetics

JF - Twin Research and Human Genetics

IS - 2

ER -