Ethnic nepotism

Ethnic nepotism is a concept in sociobiology to explain why people prefer other people of the (perceived) same ethnicity or race. Influenced by W.D. Hamilton's theory of kin selection, ethnic nepotism describes a human tendency for in-group bias or in-group favouritism applied on the ethnic level. It was coined by sociologist Pierre L. van den Berghe in response to Belgian oppression of Africans he witnessed as a Congolese-born European in the Belgian Congo.

The theory of ethnic nepotism (also see nepotism) developed by van den Berghe views ethnocentrism and racism as nepotism toward extended kin, real or fictive, and products of kin selection. In other words, ethnic nepotism points toward a biological basis for the phenomenon of people preferring others of the same ethnicity or race; it explains the tendency of humans to favor members of their own racial group by postulating that all animals evolve toward being more altruistic toward kin in order to propagate more copies of their common genes. The concept has been applied and extended by figures such as Tatu Vanhanen and Frank Salter.

To guard one's genetic interests, Frank Salter notes altruism toward one's co-ethnics:

Hamilton's 1975 model of a genetic basis for tribal altruism shows that it is theoretically possible to defend ethnic genetic interests in an adaptive manner, even when the altruism entails self sacrifice. He argued mathematically that an act of altruism directed towards the tribe was adaptive if it protected the aggregate of distant relatives in the tribe. In sexually-reproducing species a population's genetic isolation leads to rising levels of interrelatedness of its members and thus makes greater altruism adaptive. Low levels of immigration between tribes allow growing relatedness of tribal members, which in turn permits selection of of altruistic acts directed at tribal members, but only if these acts "actually aid in group fitness in some way...." Closely related individuals are less likely to free ride and more likely to invest in and thus strengthen the group as a whole, improving the fitness of its members.

Regarding how this translates into politics and why homogeneous societies are more altruistic, Frank Salter writes:

Relatively homogeneous societies invest more in public goods, indicating a higher level of public altruism. For example, the degree of ethnic homogeneity correlates with the government's share of gross domestic product as well as the average wealth of citizens. Case studies of the United States, Africa and South-East Asia find that multi-ethnic societies are less charitable and less able to cooperate to develop public infrastructure. Moscow beggars receive more gifts from fellow ethnics than from other ethnics. A recent multi-city study of municipal spending on public goods in the United States found that ethnically or racially diverse cities spend a smaller portion of their budgets and less per capita on public services than do the more homogenous cities.

Ethnic nepotism might also help to interpret phenomena like hooliganism and group fanaticism for a variety of causes. J. Philippe Rushton links ethnic nepotism to genetic similarity theory, arguing that people engage in ethnic nepotism to benefit copies of their genes, which is demonstrated by nationalism:

[B]ecause fellow ethnics carry copies of the same genes, ethnic consciousness is rooted in the biology of altruism and mutual reciprocity. Thus ethnic nationalism, xenophobia and genocide can become the ‘dark side’ of altruism. Moreover, shared genes can govern the degree to which an ideology is adopted. Some genes will replicate better in some cultures than in others. Religious, political and class conﬂicts become heated because they affect genetic ﬁtness. Karl Marx did not take his analysis far enough: ideology may be the servant of  economic interest, but genes inﬂuence both. Since individuals have a greater concentration of genetic interest (inclusive ﬁtness) in their own ethnic group  than they do in other ethnic groups, they can be expected to adopt ideas that  promote their group over others. Political ethologist Frank Salter refers to ideologies as ‘ﬁtness portfolios’, and psychologist Kevin MacDonald has described co-ethnics as engaging in "group evolutionary strategies."

Reception
In Rushton's interpretation it is not clear whether the proposed genetic likeness that supports ethnic nepotism is limited to external appearance, or it also includes other loci. If that is the case, it would be difficult to deduct how similar blood types or creatine levels, or others, among the multitude of invisible phenotype traits, contribute to determine the bonding behavior towards people carrying the alleged similar alleles. Also, there is no clue offered as to which of these specific alleles are the most important for expression of ethnic nepotism. Hamiltonian kin selection (in itself very controversial) refers exclusively to defined sets of discrete behaviors that are innate, not learned and increase the reproductive fitness among very close kin, whereas ethnic nepotism would appear to depend heavily on social interactions and on social constructs.