Abstract
The relationship between siblings is the longest and most important relationship in a person's life. The family unit, which is formed at the time of a child's birth, is a social entity that evolves and changes over time. The child, in conjunction with their parents, goes through a process of development and socialization with their siblings. Its influence on human development and personality formation has been studied by many scientists around the world. The review of research on sibling relationships in psychological science today begins with a comment on the concept of "sibling" and continues with a stop on the concepts of sibling relationships in psychological directions. Then the analysis of research in this direction in foreign, Russian and domestic psychological science was carried out. Sibling relationships may have a different character in different periods of a person's life, and the factors influencing them may also be different. Siblings take a certain position depending on the order of birth in their family. This position influences the development and formation of the sibling's personality and even the achievements he achieves in life. It is also evident that the gender of siblings also plays an important role. The article examines how the relationship between siblings is influenced by the specifics of family education, the child's attachment to the mother and the presence of a mother in siblings’ lives. At the same time, the relationship between siblings was discussed in cases where one of them had a physical or mental illness.