While the modern state may have succeeded at breaking the tribal bonds of a society that were based on kinship, we are still hard-wired to favor those closest to us.
That is why nepotism, or the showing of preferential treatment to a relative, is alive and well today. While in some cases it is against the law, and deeply unethical, nepotism is not by definition a bad thing. In fact, nepotism may not only be unavoidable in some circumstances, it may also be very positive.
Consider a family business, or the technology-driven networking tools we use. Our networks start with our families and close friends and work outward from there. The system of preferences we show for the people closest to us -- and vice versa -- are often the most important ingredients for personal and professional advancement.