Skill formation with siblings
What is your research about and why did you do it?
I study the joint production of human capital in families with siblings, where parent-child as well as sibling interactions can contribute to development during childhood. In these families, better-bonded siblings would be more connected and cooperative, which would promote pro-social behaviour among them. The importance of siblings and the quality of their bond for children's development have not been sufficiently explored, even though most children have at least one sibling. Policy has instead focused on stimulating interactions between parents and the target child. Understanding the role of siblings in the human capital formation process can provide another policy tool to tackle inequality.
How did you answer this question?
I use the Millennium Cohort Study data, which follows the lives of a representative sample of British children born in 2000–2002 and their families. Most notably, the age-5 wave provides information on how frequently siblings have positive interactions, such as when they have fun together. Using this knowledge, I can introduce a new variable called the sibling bond, which measures how well siblings get along with one another and allows me to think of both parents and siblings as players in the development process. First, I investigate if the age-5 sibling bond can explain children’s outcomes later in life. Second, I structurally estimate the production of human capital for the younger and older siblings, quantifying the contribution of the sibling bond and parental investment.
What did you find?
The main finding is that a high-quality bond between siblings matters over and beyond parental investment, with differences in the strength of the sibling bond being associated with persistent inequalities in children’s human capital. First, there is a socio-economic gradient in the quality of the sibling bond. Second, a high-quality bond between siblings at age 5 predicts better developmental, educational and health outcomes across adolescence and young adulthood. For example, I show that an increase in one standard deviation in the sibling bond at age 5 translates on average into an increase in 0.1 standard deviation in the younger sibling’s externalizing (ability to collaborate with others), internalizing (ability to focus to pursue long-term goals) and cognitive (ability to complete tasks and learn) skills across adolescence.
The figure presents: (i) the socio-economic gradient in the sibling bond at age 5 (left panel) and (ii) the point estimates in standard deviation units with the 95% confidence intervals from regressing the age-5 sibling bond on developmental outcomes across the younger sibling’s adolescence (right panel). The explanatory power of the age-5 sibling bond is robust to a large set of controls, including household characteristics, environmental factors and siblings’ skills. Results for internalizing and cognitive skills are presented in the paper.
What implications does this have for the research on wealth concentration or economic inequality?
The literature has shown how parent-child interactions and parents' abilities are contributing to the transmission of disadvantage across generations by estimating the technology of skill formation with a single child (Cunha and Heckman, 2008; Cunha, Heckman, and Schennach, 2010; Attanasio, Cattan, Fitzsimons, Meghir, and Rubio-Codina, 2020; Attanasio, Meghir, and Nix, 2020; Agostinelli and Wiswall, 2022). My work uncovers another mechanism relevant for understanding the transmission of disadvantage across generations, showing that siblings play an important role in the joint production of human capital through their interactions.
What are the next steps in your agenda?
My work offers fertile ground for developing novel interventions and policies that target siblings as well as their parents. I am working to consider such policy measures and collect new data on sibling interactions throughout the life cycle.
This paper can be cited as follows: Toppeta, A. (2022) "Skill formation with siblings." Working paper.