Child and Adolescent Twin Sudy in Sweden (CATSS)

The aim of this study is to investigate how both genetic and environmental effects influence health and behavior in children and adolescents. The CATSS was initiated in 2004. In CATSS-9, a telephone interview is conducted with consenting parents of all 1,400 twin pairs born in Sweden annually. At ages 15, 18 and 24 twins and parents are contacted again. The twins and one parent are contacted via mail containing information about the study and how to log onto a website where the survey is conducted.