Please note, due to essential maintenance online transactions will not be possible between 02:30 and 04:00 BST, on Tuesday 17th September 2019 (22:30-00:00 EDT, 17 Sep, 2019). We apologise for any inconvenience.
To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Over the last 60 years, the resources and the research in the Danish Twin Registry (DTR) have periodically been summarized. Here, we give a short overview of the DTR and a more comprehensive description of new developments in the twenty-first century. First, we outline our experience over the last decade of combining questionnaire and survey data with national demographic, social, and health registers in Statistics Denmark. Second, we describe our most recent data collection effort, which was conducted during the period 2008–2011 and included both in-person assessments of 14,000+ twins born 1931–1969 and sampling of biological material, hereby expanding and consolidating the DTR biobank. Third, two examples of intensively studied twin cohorts are given. The new developments in the DTR in the last decade have facilitated the ongoing research and laid the groundwork for new research directions.
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.
Evidence of a positive association between birthweight and IQ has been established in several studies. Analyses of within twin pair differences in birthweight and IQ have been used to shed light on the basis of the association. The strength of this approach is the possibility of controlling for both unmeasured common childhood–environmental factors as well as genetic factors shared by the co-twins. Two twin studies suggest the existence of genetic mediation between birthweight and IQ, that is, common genetic factors influence both fetal growth and IQ in childhood, while two other twin studies find no evidence of such mediation. In the present study we use a large population-based national register study of 2,413 Danish twin-pairs from birth cohorts 1986–1990, of which we have zygosity information on 74%. We perform individual level as well as intra-pair analyses of birthweight and school achievements at age 16. For both sexes we observed a monotonic increase in academic performance with increasing percentiles of birthweight. However, we did not find that this association is due to genetic mediation.
Email your librarian or administrator to recommend adding this to your organisation's collection.