Final answer:
The incest taboo is explained by the risks of inbreeding leading to deleterious mutations, the sociological benefits of expanding social networks and minimizing family conflicts, and kin selection which promotes genetic diversity.
Step-by-step explanation:
The universal incest taboo, which prohibits sexual relations between close kin, can be explained through various theories. One proposed explanation is that inbreeding would lead to the expression of deleterious mutations that result in harmful phenotypes. This is because inbreeding can increase the likelihood that offspring inherit two copies of recessive genes that cause genetic disorders or reduce fitness.
From a sociological perspective, the incest taboo also serves to direct individuals to form marital alliances outside of their immediate family, thereby expanding social networks and reducing the chances of inter-family conflict. Additionally, the taboo supports a stable family structure, which is crucial for the socialization of offspring and the provision of basic resources within a legally recognized relationship.
Kin selection further explains this taboo on a biological basis, suggesting a natural avoidance of inbreeding to increase the chances of one's genes perpetuating through subsequent generations via more distant relatives.