Abstract
Educational processes are planted into a social context that significantly determines their efficiency. Apart from the immediate social environment in which formal learning takes place, a family is one of the most crucial elements that substantially affect not only the early development but the whole educational trajectory of an individual.
The research mostly deals with the role of parents. However, also the siblings can influence educational success via the academic self-efficacy that may be affected by rivalry and mutual comparison.
By the population of university students, we proved connections between specific dimensions of siblings' relationship and respondents' selfefficacy perceived in comparison with a sibling. The findings are applicable in counselling for university students, but they also draw attention to the importance of siblings' relationships and their impact on education.