Using a large dataset with individual-level demographic information of almost 60,000 families in contemporary Finland, we analyse the regional variation and cultural assortativity by studying the network between families and the network between kins. For the network of families the largest connected component is found to consist of around 1000 families mostly originated from one single region in Western Finland. We characterize the networks in terms of the basic structural properties. In particular, we focus on the k-cores and the presence of transitive triangles. Clustering in the networks is found to result from homophily by language and religious affiliations. The large network fragments appear to be small-worlds. We also compare the fragments in the kin network with respect to the average coefficient of relationship. The measures of assortativity are able to distinguish the families in terms of their regions of origin. Overall, we distinguish between two patterns of regional effects, the ‘metropolitan’ and the ‘cultural’ pattern.