The theoretical model departs from two mechanisms that describe how family influenced people's reproductive behavior. First, family and kin might provide tangible and intangible resources, facilitating individuals to reproduce and/or protect the survival of their young offspring.
Support and resources offered by kin include alleviating the work load of pregnant or nursing women, providing assistance with child care, and improving the nutritional status of infants. Empirical research has shown that grandmothers, unmarried older aunts, and elder siblings ("helpers-at-the-nest") heightened women's fertility and promoted the survival of young children (Crognier 2001; Mace and Colleran 2008; Sear et al. 2003; Tymicki 2008; Voland and Beise 2002). On the other hand, also competition and rivalry among blood and affinal kin because of the allocation of scarce resources or parental uncertainty, might also influence couple's reproductive behavior. Secondly, family may accelerate or brake individuals' fertility through the transmission of values, preferences and attitudes on parenthood and childbearing. Fertility behavior might be transmitted from parents to children through socialization, meaning that preferences and attitudes towards family formation are instilled in the younger generation when growing up in the parental home (Duncan et al. 1965). Other family members, such as siblings, might influence fertility behavior too. The exchange of information through (un)conscious observation or conversation produces social learning when it provides additional information essential to the decision-making process. Social pressure results when the individual considers sanctions and/or benefits related to certain behavior as relevant and behaves accordingly (Bernardi 2003; Montgomery and Casterline 1996). Finally, gender roles and power relations between husband and wife also influence reproductive behavior. However, the presence and proximity of kin members are preliminary conditions for many types of support and social influence (Strier 2008). Differences and changes in the composition and dispersal of kinship networks therefore affect the opportunities for family influences on fertility. With greater dispersal, resource provision and social influence by different types of kin likely decline (Newson 2005; Turke 1989).
Figure 2. Conceptual model of family influences on reproductive behavior
Dispersal of kin, as well as their resource provision, competition and social influence, differ across family systems. Family systems are clusters of norms, values and practices surrounding family and kinship, which are geographically anchored and particular to a certain region. They can be seen, to use Wallerstein's (1991) term, as 'geocultures' and have been in place at least since the Middle Ages. Family systems differ in: 1) the interaction between parents and children (degree of authority), and 2) the relationship between siblings (degree of equality) and 3) conjugal relations (Todd 1990). Parent-child ties are connected to the speed and extent of the leaving home process, which varies between liberal ties when children depart early and authoritarian ties when leaving home is stretched out or does not occur at all. Rules of inheritance determine the nature of sibling ties, which varies between equality, in case inheritance is fully partible and all siblings inherit the same, and inequality, when property is passed on to just one child (impartible inheritance). Another way of distinguishing family systems is according to their degree of familism. In familistic societies, comprising most of southern and eastern Europe, kin ties are overall stronger than in individualistic societies (Dalla Zuanna 2001; Micheli 2000; Reher 1998).
"The Power of the Family": a conceptual model
The program's conceptual model is based on knowledge about the channels by which family shapes fertility behavior, the differential nature and strength of family ties across family systems, and economic, ideational and other determinants of fertility, such as social class, age and gender (see Figure 3). Parental resource provision and social influence likely was and is stronger and influenced fertility more strongly in communitarian and stem family systems and in Southern and Eastern Europe than in nuclear family systems and in Northwestern Europe. But whereas previous research has mainly focused on the impact of parent-child relations on fertility, the proposed program explicitly also questions the role of peer relations, i.e. sibling ties and husband-wife relations. One of the main working hypotheses of the program is that differences in the nature of peer relations across family systems might explain an important part of the regional differences in fertility levels and fertility change.Figure 3: Family types in Europe (Source: Duranton, G, A. Rodríguez-Pose and R. Sandall (2009), Family Types and the Persistence of Regional Disparities in Europe, Journal of Economic Geography 85(1):23-47).