King's College London

The Children of the Twins Early Development Study (CoTEDS) is a new prospective children-of-twins study in the UK, designed to investigate intergenerational associations across child developmental stages. CoTEDS will enable research on genetic and environmental factors that underpin parent-child associations, with a focus on mental-health and cognitive related traits. Through CoTEDS we will have a new lens to examine the roles that parents play in influencing child development, as well as the genetic and environmental factors that shape parenting behaviour and experiences. Recruitment is ongoing from the sample of approximately 20,000 contactable adult twins who have been enrolled in the Twins Early Development Study (TEDS) since infancy. TEDS twins are invited to register all offspring to CoTEDS at birth, with 554 children registered as of May 2019. By recruiting the second generation of TEDS participants, CoTEDS will include information on adult twins and their offspring from infancy. Parent questionnaire-based data collection is now underway for one- and two-year-old CoTEDS infants, with further waves of data collection planned. Current data collection includes the following primary constructs: child mental-health, temperament, language and cognitive development; parent mental-health and social relationships; parenting behaviours and feelings; and other socio-ecological factors. Measurement tools have been selected with reference to existing genetically-informative cohort studies, to ensure overlap in phenotypes measured at corresponding stages of development. This built-in study overlap is intended to enable replication and triangulation of future analyses across samples and research designs. Here, we summarise study protocol and measurement procedures and describe future plans.