If one wants to understand human social behavior in the light of evolutionary theory, one cannot avoid the concept of inclusive fitness. This essentially states that not only those genes that are passed on to the next generation through one’s own reproduction are evolutionarily significant, but also all those genes that are present in closely related individuals. In this way, behavior promoted by so-called “kin selection” can often lead to more energy and effort being invested in related individuals rather than in one’s own offspring, contributing to the emergence of highly developed social systems (eusociality). The degree of kinship used in this context is usually calculated in sociobiology on the basis of individual genes considered “selfish” in the sense of the most efficient self-replication, with the example of the propagation of a “green beard gene”, i.e., a fictitious human gene for green beards, often used to illustrate this principle (green beard effect). Apart from the fact that there is not a single phenotypic trait in the entire living world that is coded by a single gene, but always a multitude of genes involved in the expression of the structures and functions of living beings, empirical research in recent years has revealed that animals—and especially humans—are often much more social and cooperative than the classic sociobiological degree of kinship suggests. Only the extension of the concept of inclusive fitness to the totality of all genes of an individual, i.e. its genome allows a better understanding of the actual extent of animal and human social behavior. Today, freely available DNA tests, which are offered by private companies as a consequence of the worldwide booming interest in genetic family genealogies, meet this trend and could transfer the scientific exploration of human social systems to a new level.