The German Twin Family Panel TwinLife: Current State and (Epi-)genetically Informative Satellite Projects

This report provides an overview of the current state of the German twin family panel TwinLife, including information on design and sample characteristics as well as a selection of assessed constructs. TwinLife is a register-based longitudinal panel of four birth cohorts of German-speaking monozygotic and dizygotic same-sex twin pairs, and their core family members, including parents and siblings, but also partners and children of twins, if available. Using address data provided by a representative set of residents' registration offices from across Germany, twin families were identified through a multistage process. The twins were born in 1990-1993, 1997-1998, 2003-2004, and 2009-2010. They were about 5, 11, 17, and 23 years old at the time of the first survey. Designed to investigate the development of social inequalities over the life course, the TwinLife currently covers an observation period from 2014 to 2025. In the first wave, the panel included data on 4096 twin families from all parts of Germany, covering the full range of key socioeconomic indicators. Over the years, the core TwinLife project has been expanded by several satellite projects, such as the molecular genetic TwinSNPs and the TwinLife Epigenetic Change Satellite (TECS) project. TwinLife provides a unique database with a wide-ranging potential for research, since it combines a longitudinal panel with an extended twin family design, adding genetic, epigenetic and additional biological data as well as the possibility to match geographical information.