About the E-Risk Study

About the Environmental Risk (E-Risk) Longitudinal Twin Study

Our MRC funded Study aims to build knowledge around the question of how environmental and genetic factors contribute to behaviours and the development of mental health problems from childhood through to young adulthood.

About E-Risk 

The Environmental Risk (E-Risk) Longitudinal Twin Study aims to build knowledge around the question of how environmental and genetic factors contribute to the development of behaviours, health, and mental health problems from childhood through to adulthood. E-Risk was proposed in 1997 by Professor Terrie E Moffitt and Professor Avshalom Caspi and has been funded by the Medical Research Council (MRC) from 1998 through to 2027.

In 1998 E-Risk began by constructing a nationally representative 2-year birth cohort of 2,232 same-sex twins born in England and Wales in 1994-1995. Families were recruited to represent the UK population with newborns in the 1990s, to ensure adequate numbers of children in disadvantaged homes and to avoid an excess of twins born to well-educated women using assisted reproduction. The resulting study sample represents the full range of socioeconomic conditions in Great Britain; the families’ distribution is reflected on a neighbourhood-level socioeconomic index (ACORN) that very closely matches the national distribution.

The longitudinal study has concentrated on three developmental stages to date: (1) the transition to formal schooling, with assessments at ages 5 (1999-2000) and 7 years (2001-2002), retaining 98% of the cohort, (2) the transition to secondary school, with assessments at ages 10 (2004-2005) and 12 (2006-2007), retaining 96% of the cohort and (3) the transition to young adulthood, with assessments at age 18 (2012-2014), retaining 93% of the cohort. Home visits to participants before age 18 included assessments with primary caretakers as well as the participants whereas the visits at age 18 included interviews only with participants.

We will be assessing the twins again in 2024-2025 once they are 30 years of age to explore how their adult lives are taking shape. These interviews will be conducted via online video calls and our aim is to see over 90% of the cohort again. With the twins’ consent we will also arrange home visits to collect blood samples and link to their medical, mental health, education, benefits, crime, and geographical records. In 2027, the updated and anonymised dataset will be made securely available to researchers across the UK and worldwide to provide a unique resource for conducting research into mental health, adversity, and prosperity over the first three decades of life.

About E-Risk


The study of twins has been crucial to disentangle the interplay between genetics and environmental risk factors. Through the years, data have been collected about many different topics, including mental health, obesity, asthma, school performance, criminal offending, violence victimisation, neighbourhood conditions, the family environment, and also biomarkers to investigate inflammation, gene expression, epigenetic DNA methylation, telomeres, and neuropsychological functions. The repeated collection of DNA has allowed E-Risk to study the entire genetic code of individuals but also epigenetic changes across key developmental timepoints.

The E-Risk study has several innovative design features:

  1. The E-Risk birth cohort accurately represents the population of families having children in the 1990's in England and Wales.
  2. The study began looking at the participants when they were 5 years old and has access to data from birth. Beginning data collection at a young age was important, because it has been shown that problem behaviours that onset early characterise the most serious cases of adult mental disorders.
  3. Data were collected during home-visit assessments to allow for in-home collection of observational data and blood phlebotomy, to facilitate the sharing of sensitive information, and to establish a good rapport with all participants and their family to prevent attrition bias.
  4. As an innovative genetic study, E-Risk collected direct measures of an exhaustive array of putative environmental risk factors in families, schools, and neighbourhoods.
  5. As an innovative environmental study, E-Risk sampled twins. This allows us to disentangle genetic contributions from risk factors, to ascertain the true extent of their environmental effects.
  6. The E-Risk Study collected DNA; this adds measured genes to fill in the black box of genetic variance. Knowledge about how measured genes interact with environmental risks will support applied research and development of new diagnostics and treatments.
  7. Blood collection has supported the E-Risk biobank.
  8. Geo-coding of each study family’s address location has added extensive measurements of the family’s local area:  green space, crime rates, pollution exposure, poverty, and social disorganisation, among others.

E-Risk findings have informed policy and clinical practice concerning bullying, childhood psychiatric problems, breastfeeding, classroom separation of twins, child abuse and neglect, and food insecurity. It has improved the public’s understanding of science, via art and education endeavours. E-Risk research attracts prestigious prizes for both young and senior team members. It produces a strong crop of trainees launched on research and clinical career paths. It has built a strong collaborative team of senior, mid-career, and young researchers.


E-Risk permitted highly successful sub-studies that attracted funds from government agencies and charities, examining peer bullying, neighbourhoods, stress biomarkers, asthma, resilience, and epigenetics.

SCOPIC (Social Contexts of Pathways in Crime) led by Terrie Moffitt in 2002, undertook survey research with neighbours in the same postcode as each E-Risk family, to construct a data set of neighbourhood quality measures. This project was funded by ESRC.

TEDS-PEERS (Promoting Enjoyable and Engaging Relationships at School) was launched by Louise Arseneault in 2006 to investigate the impact of bullying on children’s response to stress. This project was funded by the NIHR and the Jacobs Foundation.

Germfighters led by Andrea Danese was a pilot substudy of immune-system biomarkers assayed from bloodspots in a selected sub-group of E-Risk twins.

C-strengths (Community Strengths) led by Candice Odgers was launched in 2009 to examine community-level environmental effects. This project was funded by the William T. Grant Foundation and Google.

Uncovering and confirming gene-environment interactions in psychopathology was led by Avshalom Caspi and Terrie Moffitt. Launched in 2007, it aimed to test replication across the Dunedin, Christchurch, and E-risk cohorts. This project was funded by the NIMH.

Social Inequality and Children's Mental Health was launched in 2010 to compare social inequality in the Dunedin and E-risk cohorts, and was led by Avshalom Caspi, Louise Arseneault, and Terrie Moffitt. It was funded by the ESRC and NICHD.

The Asthma Study was set up by Jonathan Mill to examine the role of genomic variation in asthma and was funded by the American Asthma Association.

Behavioural and genomic mechanisms linking childhood violence exposure to health was led by Avshalom Caspi, launched in 2013. The aim of this project was to harmonise the data sets of the E-risk and the Dunedin cohorts to support cross-cohort replication work.  For example, it achieved assays of telomeres at repeated ages, plus whole-genome methylation. This project was supported by NICHD.

The Epigenetic Impact of Psychosocial Stress Study funded jointly by ESRC and BBSRC was led by Chloe Wong and Helen Fisher to dissect the relationship between severe psychosocial stress exposure during adolescence and the epigenome.

The Resilience and Vulnerability to Childhood Maltreatment Study led by Andrea Danese and Helen Fisher aims to build a practical instrument (risk calculator) to assist professionals in identifying children who are most vulnerable to the effects of maltreatment and identify factors that could be targeted to increase their resilience. This project is jointly funded by the NSPCC and ESRC.

The Air Pollution and Mental Health Study funded by MRC, NERC, CSO, and NIHR was a collaboration between Helen Fisher, Sean Beevers and Frank Kelly (from the MRC-PHE Centre for Environment and Health). It generated high-resolution air pollution estimates based on where the twins spend most of their time to enable us to explore the impact of air pollution exposure on mental health outcomes across development.