Despite fertility decline across advanced economies over the last few decades and the increasing numbers of one-child families, little is known about the consequences of growing up without siblings. Previous research suggests that despite strong stereotypes of only children, on average, singletons do as well as children with few siblings, and better than children from large families. But since existing evidence largely comes from US research conducted during or before the 1980s, it is unclear whether it reflects current or past patterns in the UK as the selection process into only children families might vary over time and across geographical contexts. Moreover, little is known about the longer-term wellbeing of only children, and whether/how growing up without siblings might affect their life chances.

To address these gaps in knowledge, this project will analyse the effects of being an only child on both childhood and adulthood outcomes in the UK over time. Using rich data from the 1946 Medical Research Council (MRC) National Survey of Health and Development (NSHD), the 1958 National Child Development Study (NCDS), the 1970 British Cohort Study (BCS70) and the Millennium Cohort Study (MCS), the project aims to analyse the socio-demographic characteristics of only children families, compare the socio-demographic outcomes and (physical/mental) wellbeing of only children relative to the wellbeing of children growing up with siblings over time in both childhood as well as adulthood.