The Westermarck effect refers to the phenomenon where people who are raised together in close proximity during a critical period of development are less likely to develop sexual attraction to each other as adults. This effect is named after the Finnish sociologist and philosopher Edvard Westermarck, who first described it in his book “The History of Human Marriage” in 1891.
The Westermarck effect is thought to be an evolutionary adaptation that helps to prevent inbreeding and increase the genetic diversity of offspring. By reducing the likelihood of sexual attraction between family members or individuals who have grown up together, the Westermarck effect helps to increase the chances of successful mating and reproduction with partners who are genetically dissimilar.
The Westermarck effect has been observed in a number of different cultures and has been supported by a growing body of scientific research, including studies of animal behavior, human psychology, and cultural anthropology. It is often considered as one of the key factors shaping the development of human social behavior and the formation of social norms around sexual attraction and mate choice.