Definition, Background, History, and Legal, Religious and Biological Aspects
Pp. 3-30 (28)
Lutfi Jaber and Gabrielle J. Halpern
The term "consanguinity" refers to relationship by descent from the same
ancestor and means the amount of shared (identical) DNA. The term "consanguineous
marriage" refers to unions between biologically related individuals. This chapter
explores the historical, legal and religious aspects of consanguinity and discusses
genetic aspects including population genetics and molecular genetics. The types of
consanguineous unions allowed vary between different countries, and different religions
have different traditions regarding which consanguineous unions are allowed. The main
reasons for the continuation of consanguineous marriages are social and economic.
People who share a recent common ancestor share more than 99.5% of their DNA; the
closer the relatives are the more DNA they share. Once the relationship is between
fourth cousins, the original amount of shared DNA reverts to the basic amount of
99.5%. Inbreeding is measured by the inbreeding coefficient, F, which is the probability
that two genes at any locus in one individual have been inherited from a common
ancestor. Many genetic diseases are recessive, meaning only people who inherit two
abnormal genes for the same disease, one from each parent, will develop the disease.
Since close relatives have more genes in common than unrelated individuals, there is an
increased chance that parents who are closely related will carry the same disease genes
and thus have an affected child.
Autosomal recessive diseases, consanguineous marriages, cousins,
DNA, forbidden marriages, genes, inbreeding, mutations, religion.
The Bridge to Peace Community Pediatric Center, Box 27, Taibe, 40400, Israel.