Family members' and best friend's smoking influence on adolescent smoking differs between Eastern Finland and Russian Karelia.

Aims: The aim of this study was to find out whether family members' (mother, father, siblings) and best friend's smoking is related to 9th grade pupils' daily smoking in Eastern Finland and in the Pitkäranta district, in the Republic of Karelia, Russia, and whether these relations have changed in these two culturally very different neighbourhood countries from 1995 to 2013.

Methods: Data comprised four cross-sectional studies in all schools of the Pitkäranta region and selected schools in Eastern Finland. In data analyses, structural equation modelling techniques were used.