The Effect of Being the Only Child on Friendship Nominations

The literature on sociability stresses that contact with siblings may endow children with the competences needed for interacting with peers. In this paper I examine the effect of the number of siblings at home on friendship nominations at school. I use data for three countries (Germany, Netherlands, and Sweden) from the first wave of the Children of Immigrants Longitudinal Survey in Four European Countries, which targeted 18,716 pupils aged 15 years old in 480 secondary schools over England, Sweden, Germany, and the Netherlands. I employ the exponential random graph model to explore the effect of having siblings on being nominated as a friend, aggregating the estimates from individual classroom networks using meta-analysis. The estimated average effect of being the only child on forming a network tie is negative, albeit small, suggesting that some children benefit from having siblings when it comes to sociability. However, our models show that there is significant variability in the effect size across classrooms, an indication that this effect may be context dependent and that the average effect size is not a good representation the effect for all networks studied. Moreover, this effect is only marginally significant once other covariates are controlled for. I conclude that there is only weak support for social learning theory, and that there is a need to study the contextual factors mediating the effect of having siblings on sociability.