Consanguineous marriage is a type of marriage between individuals who are closely related by blood. It is a deeply rooted social trend among one-fifth of the world population, mostly residing in the Middle East, West Asia, and North Africa. In clinical genetics, a consanguineous marriage is defined as a union between two individuals who are related as second cousins or closer. The inbreeding coefficient (F) is equal to or higher than 0.0156, where (F) represents a measure of the proportion of loci at which the offspring of a consanguineous union is expected to inherit identical gene copies from both parents.
Consanguineous marriage is present in every religion and cannot be accredited to any one religious mandate. It is practiced regardless of religious influences and is a result of cultural, historical, regional, and socio-economic factors. Theories on the development of consanguineous marriage as a taboo can be supported as being both a social and a biological development. Social factors include advantages to social and financial status, upholding familial structure and assets, and ease of marital arrangements. Low age and a lack of awareness of the consequences of inbreeding are common in consanguineous marriages.
Consanguineous marriage is associated with an increased risk of genetic disorders in offspring. Children of consanguineous marriages are twice as likely to have genetic disorders as children of non-related couples. Despite this, consanguineous marriage is still practiced in many communities, particularly in rural areas compared to urban areas within the same region.
