This article analyzes the problem of high aggressiveness of adolescents from single-parent families. A high level of aggressiveness can become a factor of isolation of a teenager, low academic performance, and problems with mental well-being. Aggression of a teenager can manifest itself in a variety of forms and is a sign that a teenager is experiencing prolonged emotional stress. As part of an experimental study, it was suggested that parents from single-parent families may experience severe overstrain and this is a source of stress for a teenager. The consequence of this is an increase in the level of aggressiveness of the teenager. During the comparative analysis, data were obtained that adolescents from single-parent families have a higher level of aggressiveness, and their parents are more likely to experience emotional stress. By the method of correlation analysis, it was possible to confirm the existence of a relationship between the emotional state of the parent and the level of aggressiveness of the teenager.