This book is open access under a CC BY-NC 4.0 license.

This book is a result of an interdisciplinary, comparative project testing the hypothesis that kin will influence fertility, incorporating demography, evolutionary biology and anthropology.

It will include a review of existing literature on the subject which will show that family does matter for fertility, sometimes, but that there is considerable variation (1) in which family members matter; (2) in which fertility outcomes are affected (inter-birth intervals, age at first birth, total fertility); and (3) cross-culturally.

The empirical studies use advanced statistical techniques to develop a greater understanding of not just whether but why family matters for fertility - are relationships between family and fertility plausibly causal, and driven by helping behavior between kin? These studies will show that positive associations between family and inter-birth intervals are sometimes plausibly driven by helping behavior between kin, particularly in lower income settings; but relationships between kin and fertility in higher income contexts are less clear-cut. Further, relationships between kin may sometimes be competitive.

In the penultimate chapter, we discuss how intergenerational conflict may influence fertility outcomes, including a comparative analysis of age at first birth across 20 lower income populations suggests.