We have produced almost twenty papers, fourteen of which have been published as journal articles, working papers or as full manuscripts on SocArxiv. Moreover, we have finished one large data harmonization project (International Sibsize and Educational Attainment Database (ISEAD)
https://dataverse.harvard.edu/dataverse/isead(odnośnik otworzy się w nowym oknie)) and are close to finishing the second; in these projects we bring together more than a hundred separate surveys to create a new data base that allow us to compare the links between family size and educational attainment across birth cohorts and across countries. We also organized two workshops.
We have produced two systematic overviews of all available studies with regard to two questions that are important for the link between family size and inequalities. The first review brings together all published studies that have estimated a link between grandparents’ education and the educational attainment of their grandchildren (ie they ask whether children with highly educated grandparents reach higher levels of education themselves, taking into account the resources their parents have). We show systematically, for the first time, how strong the correlation is, how it varies between studies and between countries, and we show that after taking into account the middle generation the correlations between grandparents and grandchildren reduces more than two thirds. The second review is a meta-analysis where we have brought together all estimates of sibling correlation in educational attainment that we could find in the literature. Sibling correlations show how similar children from the same family are in terms of educational outcome. If families are more important in shaping education, no matter for what reason, siblings will be more alike. This study is the first to show the full range of sibling correlations across different studies, countries and time periods. Knowing this range helps us to interpret the results from individual studies that use sibling correlations and it tells us about countries differences in how significant the role of the family is.
Some of the main findings in our studies:
- Grandfather’s education is associated with grandchildren’s education even when taking into account resources of the parents (middle generation) but this association does not vary systemically by family size, nor is it stronger if the grandparents and grandchildren have more overlap in life time
- The range of published sibling correlations for education is 0.3-0.7 and shows only few systematic variations between countries. The correlation has not change substantially between older and younger cohorts. China is an important exception; here the sibling correlation was low in early (1940s) birth cohorts and in the next forty years increase to the higher end of the distribution.
- In the majority of countries we studied there is an increase in the disadvantage coming from a large family has for education, with only two exception (i.e. a reduction). The trend of increasing sibship size disadvantage was strongest amongst post-socialist and East Asian countries. Such a trend of growing sibship size disadvantage is not found in Nordic countries, while Anglo-Saxon countries showed a trend of decreasing sibship size disadvantage.
- Average sibship sizes have declined in virtually all countries. Fertility rates underestimate average sibship sizes. Average sibship sizes are socially stratified, with smaller sibship sizes among higher educated parents. Educational disparities in average sibship size have declined over time, indicating convergence in most countries under study. This convergence is taking place at the upper tail of the parity distribution, i.e. for large families, but not for only-child families.
- Childlessness first declines and then increase with human development in low income countries.
- The prevalence of only-children varies widely across the world and among rich countries too. In some countries only-children are rather rare, in other they are quite common. In many, but no means all countries, has the share of only-children increased. These differences in levels and trends are poorly understood so far. Only-children do better in terms of educational outcomes when there are more of them, partly because in those countries only-child families tend to have high socioeconomic status while in countries with few only-children they are more common in disadvantaged families.
- The often-found positive link between being a grandparent and well-being isn’t borne out when looking at the transition to grandparenthood, suggesting positive effects later on may be more to do with the interaction with older grandchildren than with the change in role and social status.
