While marriage between full siblings is legally prohibited in most countries worldwide, Sweden stands out as a unique partial exception where marriages between half-siblings are legally permitted.
Legal Landscape of Sibling Marriage
Globally, the marriage of siblings, particularly full siblings who share both parents, is largely legally prohibited. This widespread prohibition is rooted in various factors, including ethical, social, and genetic considerations. The strong societal taboo against full-sibling marriage is reflected in the laws of the vast majority of nations, which deem such unions unlawful.
Sweden: An Exception for Half-Siblings
Unlike the general global stance, Sweden allows for a specific type of sibling marriage. In Sweden, it is legally permissible for half-siblings to marry. This means individuals who share one common parent (either a mother or a father) but not both are allowed to enter into a marital union under Swedish law. This makes Sweden a notable outlier in the international legal landscape concerning consanguineous marriages.
The Westermarck Effect
The broad prohibition against full-sibling marriage and the general societal aversion to such unions are often explained by the Westermarck effect. This psychological phenomenon posits that individuals who are raised in close domestic proximity during early childhood, such as siblings, tend to develop an innate sexual aversion towards each other. This effect is believed to act as a natural mechanism to prevent inbreeding and promote genetic diversity, thereby reinforcing the legal and social norms against full-sibling marriages in many cultures across the globe.
