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Research has shown that the sibling constellation impacts on adult life chances. The outcomes commonly investigated are education and various forms of psychological factors such as cognitive ability. In this study we investigate an outcome relatively few have studied before – adult earnings. Three different sibling constellations are in focus: 1) being an only child, 2) having many siblings, and 3) close birth spacing between siblings. The national context is Sweden, and the study is based on administrative data, including all individuals born in the country in 1973. The outcome variable is mean labour market earnings from age 33 to 35. Using propensity score matching, we show that individuals having grown up with more than two siblings have substantially lower earnings in adulthood than those with fewer siblings. However, no significant difference was found between individuals having a closely spaced sibling and those who do not have closely spaced siblings. We also could not find any differences between only children and children with siblings.

While previous research in general observes adverse effects of siblings on children, less is known about the ways in which material circumstances condition these effects. Using propensity score matching on longitudinal data, this study estimates the effects of being an only child, being born first, and having a large sibling group on adult earnings. Estimates are made for poor and wealthy children respectively in order to examine whether effects occur for both groups. The results show that being an only child, or having a large sibling group, impacts negatively on adult earnings among poor children. Having one younger sibling furthermore has a positive effect on adult earnings among poor children. No corresponding effects were observed for wealthy children. The results indicate that sibling effects are not linear and that they are dependent on family resources.

The effects of divorce on children have been a question of significant importance for family researchers for a long time. Employing a resource theoretical perspective, this paper investigates the causal effect of parental divorce on children in the long term – specifically looking at the outcome adult labour market earnings. The analysis includes all firstborn children, born to married parents, in Sweden in 1973 (n=19,578), following them for 35 years onwards. Applying propensity score matching on longitudinal data, the analysis shows no indications of a causal effect of divorce on adult earnings.

It is not unusual with sequential partnerships today, and more children are nowadays living parts of their childhood in families consisting of both biological parents, non-parental adults, full biological siblings, and half-siblings. The aim of this study is to investigate post-divorce family re-formation regarding the effect on future labour market earnings for children. Three factors are investigated: 1) family re-formation, 2) half-siblings and 3) family size. We employ propensity score matching on a population based dataset, a method of advantage when heterogeneity in effects can be suspected. We find no evidence of effects of family re-formation, nor the occurrence of half-siblings, on labour market earnings. We find a substantial negative effect of family size on adult earnings, regardless of re-marriage and half-siblings. This suggests that the childhood circumstances that affect adult earnings are related to the nuclear family and family size – including resource dilution from siblings – regardless of whether these children originate in the nuclear family or in the divorced and re-formed family.