Also known as reverse sexual imprinting, this refers to a scientific hypothesis which states that people become desensitised sexually towards other people with whom they are in close contact during the first few years of their life. It is named after Finnish scientist Edvard Westermarck who proposed it in his 1891 book The History of Human Marriage. The Westermarck effect is used as a possible explanation for why incest is considered to be taboo in most societies. However, the prevalence of first cousin marriages in certain cultures has been used to argue that other cultural factors could offset the influence of the effect.