The problem of relationship of biological and social determinants of man's mental development is considered in the light of theoretical-psychological comprehension of the principles of genetics universal for all forms of life and most essential at the biological level of organization of the physical matter. It is necessary to distinguish between evolutionary-genetic determination of the process of man's somatic maturation and of animal's ontogenetical behavior, on the one hand, and social-historical determination of man's mental development, on the other hand. In relation to man's psyche the evolutionary-genetic process has been substituted for by the historical process as represented by the evolution of culture and, at the same time, by an uninterrupted chain of productively self-sufficient individuals ("personalities"). Meanings of the genotype and of the personality as systemic qualities of an individual which reflect his being basically integrated both into the world of living matter and into the world of social relations are discussed in this context as factors influencing man's mental development.