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Identity statement

Reference code(s)
Level of description
Collection (fonds)
Extent and medium of the unit of description (quantity, bulk, or size)
1813 boxes


Name of creator(s)

King's College London, Institute of Psychiatry

Administrative / Biographical history

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.

Immediate source of acquisition or transfer

Received from the Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, 2001-2005.

Content & structure

Scope and content

Comprising a series of questionnaires completed by parents and children participating in the TEDS project, 1994-2003; including initial contact questionnaires completed when twins were approximately one year old containing the name of mother or father, address, telephone details, consent signatures, information on twins such as whether identical or non-identical, differences in appearance, sleep patterns, feeding issues, dress, siblings, pregnancy details with diet, the health of mother, any complications and overview of the circumstances of the birth, post-natal status, levels of stress in the home, relationship between parents and their education, occupations and background, 1995-1997 (IOP/TEDS 1); questionnaires for two year old children and their parents, comprising sets of three pamphlets of around 40 pages each, completed by the mother and each twin containing questions on changes in family circumstances since last interview, illness of twins, toilet habits, juvenile self awareness, sociability, behaviour patterns, emotional state, levels of play attainment with matching shapes, colours, brick-building, drawings and puzzles completed by the children themselves, 1996-1998 (IOP/TEDS 2); questionnaires of year three surveys comprising parents' and three year old twins' booklets and consisting of basic contact details similar to previous sections, more detailed examination of the twins' behaviour such as patience, levels of anxiety, propensity for self-harm, sociability, diet, play, speech patterns, songs, nursery rhymes, discipline, with drawings by the children and tests of their vocabulary, 1997-1999 (IOP/TEDS 3); questionnaires of year four surveys, with consent and contact information, changes in the health, diet, sleep patterns, play, discipline, communications, likes and dislikes, alterations in status of parents, with a greater focus on speech development, reading ability and puzzle solving capabilities of the children, with drawings, vocabulary and puzzle-solving tests completed by the children, 1998-2000 (IOP/TEDS 4); survey booklets for the siblings sub-project investigating the development of siblings in twins families, containing year two, three and four cohorts, and comprising a sample of the total TEDS volunteer families, focusing on the development of the sibling, play, discipline, sociability, home life, vocabulary and puzzle and picture tests completed by the children, 1997-2001 (IOP/TEDS 5); various questionnaires including semi-completed forms, those without consent signatures, forms not data-inputted, opt-outs from the programme, [1996-2000] (IOP/TEDS 6); papers relating to studies used in planning the TEDS project, including studies of hemiplegia, comprising questionnaires completed by parents of sufferers for the London Hemiplegia Register, consisting of data on the health and behaviour of child sufferers, 1988-1991, questionnaires completed by teachers for the MRC Child Psychiatry Unit, requesting insight into the behaviour of children mainly in Middlesex schools, with computer printouts of statistics of the project, 1995-1997, box of audio tapes relating to a Institute of Psychiatry project, [1988] (IOP/TEDS 7); TEDS Environment (E-Risk) project papers comprising questionnaires completed by researchers during interviews with mothers and children around the age of five, and with their teachers, and consisting of a range of questions and puzzles designed to examine in more detail the background of a sample group of about 1100 twins drawn from the main register, [1999-2003] (IOP/TEDS 8).


Regular accruals

System of arrangement

The collection consists of questionnaires arranged into four sections of interviews and responses of 1, 2, 3 and 4 year-olds with additional sections on sibling and environmental sub-studies. Each twin and parent is assigned a unique identifier number that is retained throughout the course of the project. The identifier comprises a four or five digit number for each family/parent and a three number suffix unique to the individual child. Within each annual series, the questionnaires are divided into sets of three for the mother and each of the twins, colour coded between years for quick reference, and into a number of tranches comprising several hundred names arranged in broadly numerical order. These batches were created when raw questionnaires were sent for data inputting and the arrangement has been retained for ease of recovery of particular files. The Archives possess a master list of families and twins with identifier numbers and box locations. Some twins' files have been retained by the SGDP and this is noted on spreadsheet indexes.

Conditions of access & use

Conditions governing access

The collection contains sensitive personal information and medical details and is closed under statutory rules governing data protection.

Conditions governing reproduction

Collection closed to the general public.

Language/scripts of material


Finding aids

A catalogue of the contents of the collection is available online and in hard copy in the King's College Archives Reading Room on the King's Strand Campus.A series of spreadsheets indexing the contents of the collection by box number, family name and identifier code, is retained by Archives.

Allied materials

Existence and location of originals

King's College London College Archives



Further information and regular newsletters publicising the work of the Project can be downloaded from

Description control

Archivist's Note

Entry compiled by Geoff Browell for the RSLP funded AIM25 Project.

Rules or conventions

Compiled in compliance with General International Standard Archival Description, ISAD(G), second edition, 2000; National Council on Archives Rules for the Construction of Personal Place and Corporate Names 1997.

This catalogue is made available under the Open Data Commons Attribution License. This catalogue may be updated from time to time in order to reflect additional material and/or new understandings of the material.

Date(s) of descriptions

August 2005

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  • Child development
  • Developmental psychology
  • Early childhood education
  • Educational levels
  • Personality development
  • Preschool education
  • Research work

Corporate names

  • Institute of Psychiatry, King's College London
  • King's College London College Archives
  • King's College London, Institute of Psychiatry

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