Sibling similarity and relationship quality in Finland

Siblings form the strongest horizontal family tie, which often involves life-long emotional closeness and various forms of support. Similarity is often assumed to strengthen sibling relations, but existing evidence is scarce and mixed. Using data from the Generational Transmissions in Finland surveys collected in 2012, we employ both total and sibling fixed-effect regressions and examine whether sibling similarity is associated with relationship quality in two family generations: an older generation born in 1945–1950, and the generation of their children, born in 1962–1993. We study sibling similarity in gender, age, financial condition and parenthood status and measure relationship quality by contact frequency, emotional closeness and provision of practical help. In both generations, being of the same gender was associated with all relationship measures. Age similarity was also associated with more contacts and increased emotional closeness in the younger generation, and differences in parenthood status with increased provision of practical help in the older generation. In most aspects, however, sibling similarity was not associated with relationship quality. While sibling relations tend be strong in contemporary Finland, this is only partly due to similarity effects.