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.