The SKTR is an ongoing nationwide volunteer registry that collects data on South Korean twins and their families. As of 2019, the registry includes approximately 4,058 members, with participant recruitment beginning in 2001 through large maternity hospitals, twin mothers’ clubs, media advertisements, and schools. The cohorts consist of preschool-aged, school-aged, and adult twins, covering a demographic range from early childhood to young adulthood. Since its inception, the registry has continued to expand, with recent efforts focused on including twins from lower socio-economic backgrounds to ensure a diverse sample. Over the years, numerous sub-studies have been conducted using data from this registry, contributing valuable insights into various aspects of twin development, health, and behaviour.

Recruitment is ongoing