King's College London , Institute of Psychiatry

The Twins' Early Development Study (TEDS) was established in 1994 with the support of the Medical Research Council (MRC) and is based at the Social, Genetic and Developmental Psychiatry Research Centre of the Institute of Psychiatry, King's College London. It was set up to investigate the development of three common psychological problems in children: communication disorders, mild mental impairment and behaviour problems, using sets of twins to test the relative importance of environmental and genetic causation in determining their onset, with autism as a main line of enquiry. Studies also include the process of skill development such as language skills and story telling. The project comprises initial and yearly follow-up face to face and telephone interviews and written responses taken from around 16,000 pairs of twins born in England and Wales between 1994 and 1996 and their parents and teachers, and more lengthy and detailed responses from the parents of those children who developed problems.

The twins were identified and located by the Office for National Statistics, which manages the principal name list. This data has been combined with genetic sampling to gauge the contribution of inheritance to language and cognitive development. The study is one of the largest of its kind in the world and also comprises a number of working groups using samples of raw data from smaller cohorts to analyse specific aspects of the behavioural development of young children. Notably, groups are investigating the influence of other siblings in the twins' home lives and on `Environmental Risk' factors in child development.