The development of pedagogical-psychological theories causes an increase in the number of examined factors (cognitive and non-cognitive). One of the non-cognitive factors is the family environment, so the paper deals with determining the connection between success in physics and mathematics and family functioning. In the research, 80 seventh and eighth-grade elementary school students participated. The constructed questionnaire included eight dimensions of family functioning: cohesion, flexibility, disunity, networking, chaos, rigidity, family communication, and family satisfaction. Results showed that students whose parents are married achieve significantly higher scores on all four mentioned scales. The children whose parents are divorced achieved the lowest marks. Also, the dimensions of communication and family satisfaction are rate as good. The chaotic component was influenced by parents‘ level of education, where the highest value was expressed by students whose parents are at the primary school level. This component proved to be important for students’ achievements in mathematics. Achievements in physics were influenced by the level of cohesion, whose increase also caused a higher student achievement. Family environment is an important factor determining students’ development, functioning, and school success, so it is important to monitor its impact and train teachers to work with students from dysfunctional families.