The number of children who will ever have a half sibling is increasing. Both full and half siblingships has the potential to develop into enduring and important social relationships, providing that they overlap in time and space during childhood. It is not known, however, what proportion - out of the population that will ever have a half siblings - that potentially could engage in long-term social interaction with a half- sibling during childhood. This study estimates the boundaries of accumulated exposure to full and half siblings across childhood. I use Swedish register data to provide a broad overview of the upper and lower bounds of the probability of full- and half-sibling exposure from age zero to 18, estimated by age overlap and registered co-residence for all full and half siblings of a complete birth cohort. I find that a among all children who will ever have a half-sibling, a substantive share is most likely prevented from persistent social interaction with their half-sibling(s). This is due to lengthy cross-partner birth spacing and plausibly also due to gendered custodianship patterns. I show that these patterns do not differ substantially across socioeconomic groups. I demonstrate that individuals who are exposed to half siblings for a long time have very particular sibling-set configurations. This study is the first to quantify the role of birth spacing and residency patterns for the exposure to full and half siblings across childhood. It highlights the benefits of including a population perspective for understanding half sibling social relationships.
Presented in Session 110. Life Course: Linked Lives