The article is to take a scientific reflection on the specific nature of marriage and the family as a natural system at the turn of the twentieth and twenty-first centuries. The family can be seen in various aspects. Hence, we are talking about terms sociobiological naturalism, psychodynamic, learning, contextual approach and the approach system. The family as a natural system has its own characteristics, which together are the fundamental criteria for its analysis and description. These properties may include such as the principle of balance of power, identity, adaptability, shaping roles, hierarchical organization, ownership control, the properties of a rigid, cohesive system, organization, mechanization, centralization, domination, dynamism, variability, evolution. The last part of the article is devoted to the important elements related to the analysis of the transformation of the family system at the turn of the century.