Title: Are only children all right? A cross-cohort analysis on the well-being of only children in the UK
Funder: Economic and Social Research Council

Abstract: One child families are becoming more common in the U.K. Although several studies suggest that only children fare well in childhood compared to their peers with siblings, existing evidence largely comes from U.S. research conducted during or before the 1980s. It is unclear whether it applies to current or past patterns in the U.K. since the context in which only child families are formed may vary over time and space. Moreover, very little is known about the longer-term well-being of only children. I propose an innovative programme of research to analyse comprehensively the effects of being an only child, i.e. a child with no (biological, step or adopted) siblings, on outcomes in both childhood and adulthood in the U.K. through uniquely rich data which enable me to study these associations over time. The project will use data from four longitudinal birth cohort studies: the 1946 National Survey of Health and Development (NSHD), the 1958 National Child Development Study (NCDS), the 1970 British Cohort Study (BCS) and the Millennium Cohort Study (MCS). The project has four main objectives: Objective 1 (project A): Using data from the first wave of the four cohort studies, the first aim is to reveal what are the socio-demographic (such as education, social class, parental age and family structure) characteristics of only child families and whether and how they have changed over time. A cross-cohort perspective is crucial since the context in which only children families are formed has changed markedly over time. Objective 2 (project B): Using data from the four cohort studies, the second aim is to compare the well-being of only children relative to the well-being of children growing up with siblings and whether the association has changed over time. The focus will be on cognitive outcomes that are collected during childhood and adolescence in the four datasets, in order to maximize comparability across the cohort studies. Using latent growth curve and linear regression models, the associations will be analysed both before and after adjustment for parental characteristics which will enable me to partially isolate the effect of being an only child from the characteristics of one child families, which may have changed over time. Objective 3 (project C): Using data from several waves of the NSHD, NCDS and BCS the third aim will be to analyse the longer-term well-being of only children. I will analyse the socio-economic (such as education), demographic (such as union formation/union, the transition to parenthood and the timing thereof) and health outcomes of only children over the life course and across cohorts. Depending on the nature of the outcome, associations will be tested using event history and linear/logistic regression models both before and after the inclusion of family background characteristics. Objective 4 (project D): Using data from the older cohort studies only, the NSHD and the NCDS, the fourth aim will be to analyse the mental, physical health and loneliness of only children at older ages compared to cohort members who grew up with siblings. Associations will be tested using linear or logistic regression models depending on the nature of the outcome, both before and after the inclusion of family background characteristics. This is an important and ambitious project which, in addition to maximize the impact and value of the U.K. birth cohort studies, has the potential to produce ground breaking results which will impact future research as they will be immediately relevant to the scientific literature which has neglected this demographic group for the last 30 years. It has also the potential to make a significant contribution to society more widely as its findings will be immediately relevant to third-sector organizations and government bodies which aim to improve the well-being of vulnerable children and of older people at risk of loneliness and to only children families.

Lay abstract: One child families are becoming more common in many advanced societies, including the UK. 18% of U.K. women who were born around 1970 had only one child, in contrast to 13% who were born around 1945 (i.e. their mothers' generation). Previous research suggests that despite strong negative stereotypes of only children (which characterize them as spoiled, overprotected and lonely due to lack of siblings), on average, only children do as well as children with few siblings and better than children from large families. However, existing evidence largely comes from U.S. research conducted during or before the 1980s and it is unclear whether it applies to current or past patterns in the U.K. since the context in which only child families are formed and their characteristics may vary over time and space. Moreover, very little is known about the longer-term well-being of only children and whether growing up without siblings may affect their life chances and well-being in older ages. To address these gaps in knowledge, I propose an innovative programme of research to study the effects of being an only child in childhood and adulthood in the UK. The project uses data from four UK longitudinal datasets: the 1946 National Survey of Health and Development (NSHD), the 1958 National Child Development Study (NCDS), the 1970 British Cohort Study (BCS) and the Millennium Cohort Study (MCS) which follows a group of children born in 2000-2002. These are large surveys which follow the lives the cohort members from birth onwards. The project has four main objectives: 1) to analyse the socio-demographic characteristics of only children families and whether and how they have changed over time; 2) to compare the well-being (e.g. cognitive) of only children relative to the well-being of children growing up with siblings over time; 3) using data from the 1946, 1958 and 1970 cohort studies to analyse the social/demographic characteristics (e.g. education, fertility, partnership trajectories) and health of only children over the life course; 4) using data from the 1946 and 1958 cohort studies to analyse the well-being (e.g. health, social support, loneliness) of only children in older age. The proposed project will be undertaken at the Institute for Social and Economics Research (ISER) at the University of Essex under the mentorship of the director of ISER Prof. Emily Grundy. ISER, a centre of excellence in the production and analysis of longitudinal studies, will provide excellent research support given its strong team of demographers, epidemiologists, statisticians and economists. An advisory board has been set up which includes representation from academic and non-academic members: the UK Ministry of Justice, the Children's Society, the National Children's Bureau and CLOSER (based at UCL). The advisory board will be involved throughout the process by providing input into the research and by promoting the dissemination and impact of the project's findings. The project will produce at least four academic papers which will be submitted to and published in leading demography/sociology/public health journals, presentation of the project's findings at eight academic conferences, and other dissemination activities such as producing press releases to be sent to high quality media and disseminating the project's findings through social media. This is the first comprehensive project on the well-being of only children in the U.K. and it has the potential to make a significant contribution not only to the scientific literature but also to society as its findings will be immediately relevant to third sector organizations working with children and adults, government departments designing policies to improve the lives of troubled children and of older people at risk of loneliness and only children families themselves. The project will also enable the principal investigator to transition to full independent investigator status.

Research activity codes: 2.4 SURVEILLANCE AND DISTRIBUTION
Health categories: GENERIC HEALTH RELEVANCE