The K2ID-Twins survey data will be made available to scientific users after the end of the project. For information on how researchers can obtain access to the data, please contact the principal investigators: Professor C. Katharina Spiess (kspiess@diw.de), Professor Pia Schober (pia.schober@uni-tubingen.de) and Professor Martin Diewald (martin.diewald@uni-bielefeld.de).