Intergenerational correlation of effective family size in early Québec (Canada)

The use of a comprehensive demographic database of the early French Canadian population (1608-1800) reveals an almost null impact of parents' fertility on children's fertility (r approximately 0.01-0.05), which contradicts the commonly held view that family size has a tendency to run in families. However, in this population, there is a clear transmission from one generation to the next of the effective family size within a given geographical area (EFS, defined as the number of children that settle per settled individual). Three types of correlations between EFS of parents and children are presented in order to account for the impact of socio-demographic differentials. Individuals who belong to a large sibship and who settled in a given subdivision tend to encourage the settlement of a high number of their own children in the same subdivision (r approximately 0.1-0.3). An additional correlation was introduced to see if geographically-based differentials of EFS can account for the differential of founders' regional genetic contribution. The analysis shows that EFS correlation has a definite impact on the concentration of a population's gene pool (it increases it by approximately 20%-45%), and partly accounts for the differences between subdivisions in this regard.