This population-based study of Finnish twins born 1983–1987 was identified through Finland’s Central Population Registry. A total of 2,705 families (87% of all identified) were enrolled and twins were invited to participate in mailed surveys at ages 12, 14, 17–18, 21–26, and 34–40. An intensively studied subset (1035 families) was selected for genotyping and additional interviews. All participants and their families provided informed consent/assent, including written informed consent for all those who provided blood or saliva samples for DNA genotyping. The study was approved by the Indiana University Institutional Review Board and by the Helsinki University Hospital (HUS) Regional Ethics Committee. Full details on data collection have been previously published (35). The current study includes n=1,219 EUR participants with genetic data passing quality control.
