Endogamy is the cultural practice of mating within a specific
social group,
religious denomination,
caste, or
ethnic group, rejecting any from outside of the group or belief structure as unsuitable for marriage or other close personal relationships. Its opposite,
exogamy, describes the social norm of marriage outside of the group.
Endogamy is common in many cultures and ethnic groups. Several
religious and
ethnic religious groups are traditionally more endogamous, although sometimes mating outside of the group occurs with the added dimension of requiring
marital religious conversion. This permits an exogamous marriage, as the convert, by accepting the partner's religion, becomes accepted within the endogamous group. Endogamy, as distinct from
consanguinity, may result in transmission of
genetic disorders, the so-called
founder effect, within the relatively closed community.
Endogamy can encourage
sectarianism and serves as a form of self-segregation. For instance, a community resists integration or completely merging with the surrounding population. Minorities can use it to stay ethnically homogeneous over a long time as distinct communities within societies that have other practices and beliefs.
The
isolationist practices of endogamy may lead to a group's extinction, as genetic diseases may develop that can affect an increasing percentage of the population. However, this disease effect would tend to be small unless there is a high degree of close inbreeding, or if the endogamous population becomes very small in size.
Social dynamics
The
Urapmin, a small tribe in
Papua New Guinea, practice strict endogamy. The Urapmin also have a system of kinship classes known as tanum miit. Since the classes are inherited
cognatically, most Urapmin belong to all of the major classes, creating great fluidity and doing little to differentiate individuals.[1]
The small community on the
South Atlantic island of
Tristan da Cunha are, because of their geographical isolation, an almost endogamic society. There are instances of health problems attributed to endogamy on the island, including
glaucoma and
asthma as research by the
University of Toronto has demonstrated.[2]
Genealogy
Endogamic marriage patterns may increase the frequency of various levels of
cousin marriage in a population, and may cause high probability of children of first, second, third cousins, etcetera.
If a cousin marriage has accrued in a known ancestral tree of a person, in historical time, it is referred to as
pedigree collapse. This may cause relations along multiple paths between a person's autosomal-DNA matches. It creates stronger DNA matches between the DNA matches than expected from the nearest path.[3]
Cousin marriage should not be confused with
double cousins, which do not cause a pedigree collapse. Certain levels of
sibling marriage and cousin marriage is prevented by law in some countries, and referred to as
consanguinity.
A long term pattern of endogamy in a region may increase the risk of repeated cousin marriage during a long period of time, referred to as
inbreeding. It may cause additional noise in the DNA autosomal data, giving the impressions that DNA matches with roots in that region are more closely related than they are.
Examples
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Examples of ethnic and religious groups that have typically practiced endogamy include:
Lepcha, an ethnic group in India, Nepal, and Bhutan
Judaism traditionally mandates religious endogamy, requiring that both marriage partners be Jewish, while allowing for marriage to converts.
Orthodox Judaism maintains the traditional requirement for
endogamy in Judaism as a binding,[12] inherent part of Judaism's religious beliefs and traditions.[13]
The
Knanaya, an endogamous group within the
St. Thomas Christian Community of India. The community claims to have arrived to India in the fourth century and have been noted for their historical practice of endogamy.[citation needed]
^Robbins, Joel (2004). Becoming Sinners: Christianity and Moral Torment in a Papua New Guinea Society. University of California Press. pp. 191–192.
ISBN0-520-23800-1.