The most basic community of humans is the family. Multiple families working together form a tribe. Tribes can gather together to form larger communities — clans, city-states and nations. This is, in a general sense, the pattern of human civilization. But the family remains the basic unit, and because humans are animals too, we are also subject to kin selection, an instinctive desire to support family members over unrelated people, no matter how big or powerful our larger communities become. So, a tension between loyalty to family and loyalty to the state has always been an important part of human civilizations.
There are plenty of examples. Confucianism is a school of political thought and philosophy that forms a vital part of the foundation of Chinese civilization, and a lot of Confucian writings emphasize family loyalty. But this loyalty had to be balanced with a concern for the general well-being of the state. Nepotism served as a counterbalance to growing imperial power in different Chinese eras; Confucianism even suggests a little nepotism is a good thing [source: Marsh]. Later attempts to eliminate nepotism in favor of a "purer" communist meritocracy gave government officials such unchecked power that they were able to freely promote family members regardless of qualification. The attempt to eliminate nepotism paradoxically caused an explosion of nepotism and corruption.
Both the Roman Republic and Empire were tangled webs of nepotism. Nepotism was essentially the vehicle for transmission of power, with noble families passing their wealth, lucrative businesses and powerful political positions to their sons and other relatives. The sway of nepotism in Rome grew and faded over the generations, but it was always present and is sometimes cited as a key contributor to the empire's eventual collapse. The promotion of incompetent relatives to important positions made it impossible to govern such a large and complex empire, so the empire gradually became more corrupt until it failed completely [source: Matyszak]. One of the most infamous events in world history, the assassination of the Roman politician Julius Caesar, involved nepotism. Instead of appointing a close political ally, Caesar willed his position as dictator and his fortune to a grandnephew, Octavian, who would become the first Roman emperor and take the name Caesar Augustus.
Similar tensions have played out in modern eras. In India, the Nehru-Gandhi family has held power for generations. In President Suharto's Indonesia, corruption was so widespread it gained its own abbreviation, KKN — which in Indonesian stands for "corruption, collusion and nepotism" — and led eventually to Suharto resigning. In the U.S., John F. Kennedy named his own brother, Robert Kennedy, U.S. attorney general despite his brother having no experience in the state or federal courts (though he had worked as a Justice Department attorney and Senate committee counsel.) And President Donald Trump named his own daughter and son-in-law to high-level government positions, despite their having no government experience [sources: Bellow, Greenlees, Joseph].
Nepotism has been hard at work in many other nations and eras, too, especially those where corruption was a problem. Or it hasn't been doing any work, since it got the job from its uncle and knows it can't really be fired.