Age differences in entry into parenthood among siblings and cousins in Dutch and Finnish kinship networks

With fewer siblings and cousins sharing longer lifespans, their relationships may become increasingly important sources of social influence and support in ageing societies. This study makes an empirical and methodological contribution by comparing and analyzing the association of horizontal kin’s timing of entry into parenthood in two European countries: the Netherlands and Finland. We investigate whether horizontal kin being closer in degree of relatedness, share maternal lineage and have the same gender, are more likely to have their first child at approximately the same age. Our results show that cousins are more similar to full siblings in their age at first birth than we expected, whereas half-siblings have the largest age difference. Moreover, same sex kin pairs, except half-siblings, are closest in age at first birth. Besides this substantive contribution, this study serves as a methodological blueprint. In a handful of Western European countries, a new data source has recently become available that allows empirical analysis of kinship networks across the entire population. To our knowledge, this study is the first to apply statistical methods to analyze and compare horizontal kinship networks across different European contexts.