Cousin

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A cousin is a relative that is the child of a parent's sibling; this is more specifically referred to as a first cousin.

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More generally, in the kinship system used in the English-speaking world, a cousin is a type of relationship in which relatives are two or more generations away from their most recent common ancestor. For this definition degrees and removals are used to further specify the relationship.

Degree measures how distant the relationship is from the most recent common ancestor(s). If the cousins do not come from the same generation, removal is specified, as removal measures the difference in generations between the two cousins. When the removal is not specified, no removal is assumed. [1] [2]

Various governmental entities have established systems for legal use that can precisely specify kinship with common ancestors any number of generations in the past; for example, in medicine and in law, a first cousin is a type of third-degree relative.[ citation needed ]

Basic definitions

Queen Victoria and her cousin Princess Victoria, Duchess of Nemours, 1852 Victoria and her cousin, 1852.jpg
Queen Victoria and her cousin Princess Victoria, Duchess of Nemours, 1852

People are related with a type of cousin relationship if they share a common ancestor, and are separated from their most recent common ancestor by two or more generations. This means neither person is an ancestor of the other, they do not share a parent (are not siblings), and neither is a sibling of the other's parent (are not the other's aunt/uncle nor niece/nephew). [2] In the English system the cousin relationship is further detailed by the concepts of degree and removal.

The degree is the number of generations subsequent to the common ancestor before a parent of one of the cousins is found. This means the degree is the separation of the cousin from the common ancestor less one. Also, if the cousins are not separated from the common ancestor by the same number of generations, the cousin with the smallest separation is used to determine the degree. [1] The removal is the difference between the number of generations from each cousin to the common ancestor. [1] Two people can be removed but be around the same age due to differences in birth dates of parents, children, and other relevant ancestors. [1] [3] [4]

Basic family tree
JosephEdwinaOrder
1st
PaulMarieCharlesClaudette2nd
3rd
DaisyDavidEmmaEdward
FelicityFrankGeorgeGwen
HarryIngeborg
  • The relationship between every solid shaded box and a similar one on the other branch of the tree is that of a cousin.
  • The removal is the number of rows by which the relatives are separated.
  • The degree of the relationship is that of the relative with the lowest order.
  • The rules are the same for cousins-in-law, except they exist between shaded solid lines and shaded dotted lines.

For example, David and George are on opposing sides of the family tree and are first cousins (David is of the lowest order: one) with one removal (the cousins are of order one and two respectively; therefore, the difference in generations to the common ancestor is one).

Additional terms

Gender-based distinctions

A maternal cousin is a cousin that is related to the mother's side of the family, while a paternal cousin is a cousin that is related to the father's side of the family. This relationship is not necessarily reciprocal, as the maternal cousin of one person could be the paternal cousin of the other. In the example Basic family tree, Emma is David's maternal cousin and David is Emma's paternal cousin.

On the other hand, parallel and cross cousins are reciprocal relationships. Parallel cousins are descended from same-sex siblings. A parallel first cousin relationship exists when both the subject and relative are maternal cousins, or both are paternal cousins. Cross cousins are descendants from opposite-sex siblings. A cross first cousin relationship exists when the subject and the relative are maternal cousin and paternal cousin to each other. [9] In the basic family tree example, David and Emma are cross cousins.

Multiplicities

OttoLouiseRichardBeatrice
ClaudetteHenryAlfredDorothy
EdwinFrances
Edwin and Frances are double first cousins because they share both sets of grandparents as they are cousins through both parents. They are cousins through the siblings Claudette and Alfred as well as the siblings Henry and Dorothy.

Double cousins are relatives who are cousins from two different branches of the family tree. This occurs when siblings, respectively, reproduce with different siblings from another family. [10] This may also be referred to as "cousins on both sides". The resulting children are related to each other through both their parents and are thus doubly related. Double first cousins share both sets of grandparents.

WilliamAliceAnthony
BenjaminAnneRobertCecilie
DavidPenelope
David and Penelope are half cousins because they share only one grandparent (Alice) because they are related through half-siblings (Anne and Robert).

Half cousins are descended from half siblings and would share one grandparent. [11] The children of two half siblings are first half cousins. If half siblings have children with another pair of half siblings, the resulting children would be double half first cousins and would share one grandparent on each side.

While there is no agreed upon term, it is possible for cousins to share three grandparents if a pair of half siblings had children with a pair of full siblings. [12] [13]

Non-blood relations

PeterAnne
ArthurElizabethCharlesKarenColin
David{{{Blk}}}{{{Blk}}}Mary
David and Mary are step-cousins because David's uncle (Charles) is now Mary's stepfather, Mary's mother (Karen) having married Charles.

Step-cousins are either stepchildren of an individual's aunt or uncle, nieces and nephews of one's step-parent, or the children of one's parent's step-sibling. [14] A cousin-in-law is the cousin of one's spouse or the spouse of one's cousin. [15]

Consanguinity

Consanguinity is a measure of how closely individuals are related to each other. It is measured by the coefficient of relationship. Below, when discussing the coefficient of relationship, we assume the subject and the relative are related only through the kinship term. A coefficient of one represents the relationship one has with oneself. Consanguinity decreases by half for every generation of separation from the most recent common ancestor, as there are two parents for each child. When there is more than one common ancestor, the consanguinity between each ancestor is added together to get the final result. [16]

Between first cousins, there are two shared ancestors each with four generations of separation, up and down the family tree: ; their consanguinity is one-eighth. For each additional removal of the cousin relationship, consanguinity is reduced by half, as the generations of separation increase by one. For each additional degree of the cousin relationship, consanguinity is reduced by a quarter as the generations of separation increase by one on both sides. [16]

Half cousins have half the consanguinity of ordinary cousins as they have half the common ancestors (i.e. one vs two). Double cousins have twice the consanguinity of ordinary cousins as they have twice the number of common ancestors (i.e. four vs two). Double first cousins share the same consanguinity as half-siblings. Likewise, double half cousins share the same consanguinity as first cousins as they both have two common ancestors. If there are half-siblings on one side and full siblings on the other, they would have three-halves the consanguinity of ordinary first cousins. [16]

In a scenario where two monozygotic (identical) twins have children with another pair of monozygotic twins, the resulting double cousins would test as genetically similar as siblings.

Cousin marriage

Cousin marriage is important in several anthropological theories, which often differentiate between matriarchal and patriarchal parallel and cross cousins.

Currently about 10% and historically as high as 80% of all marriages are between first or second cousins. [17] [18] Cousin marriages are often arranged. [17] [18] [19] [20] [21] Anthropologists believe it is used as a tool to strengthen the family, conserve its wealth, protect its cultural heritage, and retain the power structure of the family and its place in the community. Some groups encourage cousin marriage while others attach a strong social stigma to it. In some regions in the Middle East, more than half of all marriages are between first or second cousins (in some of the countries in this region, this may exceed 70%). [22] Just outside this region, it is often legal but infrequent. Many cultures have encouraged specifically cross-cousin marriages. [23] In other places, it is legally prohibited and culturally equivalent to incest. [24] [25] Supporters of cousin marriage often view the prohibition as discrimination, [26] [27] while opponents claim potential immorality. [28]

Reproduction

Couples that are closely related have an increased chance of sharing genes, including mutations that occurred in their family tree. If the mutation is a recessive trait, it will not reveal itself unless both father and mother share it. [29] Due to the risk that the trait is harmful, children of high-consanguinity parents have an increased risk of recessive genetic disorders.

Closely related couples have more children. Couples related with consanguinity equivalent to that of third cousins have the greatest reproductive success. [30] This seems counterintuitive as closely related parents have a higher probability of having offspring that are unfit, yet closer kinship can also decrease the likelihood of immunological incompatibility during pregnancy. [31]

This risks of inbreeding - particularly through common practice of cousin marriage - extend beyond the immediate descendants of those involved. Sustained cousin marriage within a population group over generations eventually leads to inbreeding at the population level and the rise of genetic disorders that affects the entire population, not just those in cousin marriages. [32] Increased genetic literacy within a population can lead to a reduction in cousin marriage. [33] [34]

See also

Related Research Articles

Incest is sex between close relatives, for example a brother or sister or cousins. This typically includes sexual activity between people in consanguinity, and sometimes those related by lineage. It is condemned and considered immoral in most societies, given that it can lead to an increased risk of genetic disorders in children in case of pregnancy from incestuous sex.

<span class="mw-page-title-main">Inbreeding</span> Reproduction by closely related organisms

Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid inbreeding only rarely.

<span class="mw-page-title-main">Kinship</span> Web of human social relationships

In anthropology, kinship is the web of social relationships that form an important part of the lives of all humans in all societies, although its exact meanings even within this discipline are often debated. Anthropologist Robin Fox says that the study of kinship is the study of what humans do with these basic facts of life – mating, gestation, parenthood, socialization, siblingship etc. Human society is unique, he argues, in that we are "working with the same raw material as exists in the animal world, but [we] can conceptualize and categorize it to serve social ends." These social ends include the socialization of children and the formation of basic economic, political and religious groups.

<span class="mw-page-title-main">Sibling</span> One of two or more individuals having at least one parent in common

A sibling is a relative that shares at least one parent with the other person. A male sibling is a brother, and a female sibling is a sister. A person with no siblings is an only child.

<span class="mw-page-title-main">Consanguinity</span> Property of being from the same kinship as another person

Consanguinity is the characteristic of having a kinship with a relative who is descended from a common ancestor.

An ancestor, also known as a forefather, fore-elder, or a forebear, is a parent or (recursively) the parent of an antecedent. Ancestor is "any person from whom one is descended. In law, the person from whom an estate has been inherited."

The coefficient of relationship is a measure of the degree of consanguinity between two individuals. The term coefficient of relationship was defined by Sewall Wright in 1922, and was derived from his definition of the coefficient of inbreeding of 1921. The measure is most commonly used in genetics and genealogy. A coefficient of inbreeding can be calculated for an individual, and is typically one-half the coefficient of relationship between the parents.

<span class="mw-page-title-main">Pedigree collapse</span> Concept in genealogy

In genealogy, pedigree collapse describes how reproduction between two individuals who share an ancestor causes the number of distinct ancestors in the family tree of their offspring to be smaller than it could otherwise be. Robert C. Gunderson coined the term; synonyms include implex and the German Ahnenschwund.

<span class="mw-page-title-main">Affinity (Catholic canon law)</span> Concept in impediments to marriage

In Catholic canon law, affinity is an impediment to marriage of a couple due to the relationship which either party has as a result of a kinship relationship created by another marriage or as a result of extramarital intercourse. The relationships that give rise to the impediment have varied over time. Marriages and sexual relations between people in an affinity relationship are regarded as incest.

A person's next of kin (NOK) may be that person's spouse, adopted family member or closest living blood relative. Some countries, such as the United States, have a legal definition of "next of kin". In other countries, such as the United Kingdom, "next of kin" may have no legal definition and may not necessarily refer to blood relatives at all.

In law and in cultural anthropology, affinity is the kinship relationship created or that exists between two people as a result of someone's marriage. It is the relationship each party in the marriage has to the family of the other party in the marriage. It does not cover the marital relationship itself. Laws, traditions and customs relating to affinity vary considerably, sometimes ceasing with the death of one of the marriage partners through whom affinity is traced, and sometimes with the divorce of the marriage partners. In addition to kinship by marriage, "affinity" can sometimes also include kinship by adoption or a step relationship.

<span class="mw-page-title-main">Chinese kinship</span> System of family relationships in China

The Chinese kinship system is among the most complicated of all the world's kinship systems. It maintains a specific designation for almost every member's kin based on their generation, lineage, relative age, and gender. The traditional system was agnatic, based on patriarchal power, patrilocal residence, and descent through the male line. Although there has been much change in China over the last century, especially after 1949, there has also been substantial continuity.

A cousin marriage is a marriage where the spouses are cousins. The practice was common in earlier times and continues to be common in some societies today, though in some jurisdictions such marriages are prohibited. Worldwide, more than 10% of marriages are between first or second cousins. Cousin marriage is an important topic in anthropology and alliance theory.

In law, a prohibited degree of kinship refers to a degree of consanguinity, or sometimes affinity between persons that makes sex or marriage between them illegal.

Kinship terminology is the system used in languages to refer to the persons to whom an individual is related through kinship. Different societies classify kinship relations differently and therefore use different systems of kinship terminology; for example, some languages distinguish between consanguine and affinal uncles, whereas others have only one word to refer to both a father and his brothers. Kinship terminologies include the terms of address used in different languages or communities for different relatives and the terms of reference used to identify the relationship of these relatives to ego or to each other.

<span class="mw-page-title-main">Family</span> Group of related people

Family is a group of people related either by consanguinity or affinity. It forms the basis for social order. Ideally, families offer predictability, structure, and safety as members mature and learn to participate in the community. Historically, most human societies use family as the primary purpose of attachment, nurturance, and socialization.

Laws regarding incest vary considerably between jurisdictions, and depend on the type of sexual activity and the nature of the family relationship of the parties involved, as well as the age and sex of the parties. Besides legal prohibitions, at least some forms of incest are also socially taboo or frowned upon in most cultures around the world.

<span class="mw-page-title-main">Cousin marriage in the Middle East</span>

Cousin marriage is a form of consanguinity. While consanguinity is not unique to the Arab or Islamic world, Arab countries have had "some of the highest rates of consanguineous marriages in the world". The bint 'amm marriage, or marriage with one's father's brother's daughter is especially common, especially in tribal and traditional Muslim communities, where men and women seldom meet potential spouses outside the extended family. Rates of cousin marriage in the Middle East have been found to vary from 29% in Egypt to nearly 58% in Saudi Arabia.

The concept of nurture kinship in the anthropological study of human social relationships (kinship) highlights the extent to which such relationships are brought into being through the performance of various acts of nurture between individuals. Additionally the concept highlights ethnographic findings that, in a wide swath of human societies, people understand, conceptualize and symbolize their relationships predominantly in terms of giving, receiving and sharing nurture. The concept stands in contrast to the earlier anthropological concepts of human kinship relations being fundamentally based on "blood ties", some other form of shared substance, or a proxy for these, and the accompanying notion that people universally understand their social relationships predominantly in these terms.

An avunculate marriage is a marriage with a parent's sibling or with one's sibling's child—i.e., between an uncle or aunt and their niece or nephew. Such a marriage may occur between biological (consanguine) relatives or between persons related by marriage (affinity). In some countries, avunculate marriages are prohibited by law, while in others marriages between such biological relatives are both legal and common, though now far less common.

References

  1. 1 2 3 4 King, Robert C.; Stansfield, William D. (2013). "Cousin". A Dictionary of Genetics. Oxford University Press. 8.
  2. 1 2 "Cousin Definition & Meaning". Merriam-Webster .
  3. ↑ "What is a First Cousin, Twice Removed?". Genealogy.com. Retrieved Sep 26, 2015.
  4. ↑ "Genetic And Quantitative Aspects Of Genealogy – Types Of Collateral Relationships". Genetic-genealogy.co.uk. Retrieved 28 October 2014.
  5. ↑ "Full cousin definition and meaning". Collins English Dictionary . Retrieved 2024-08-04.
  6. ↑ "Cousin-german definition and meaning". Collins English Dictionary . Retrieved 2024-08-04.
  7. ↑ Vilas, Charles Harrison (1875). Genealogy of the Descendants of Peter Vilas. Madison, Wis: The editor. p. 17.
  8. 1 2 Harry Loewen (1988). Why I am a Mennonite: Essays on Mennonite identity. Herald Press. p. 286. ISBN   083613463X. They seemed to treasure genetic relations in a way I had not encountered before, using such relational designations as "cousin-uncle." They spoke of Mennonite names, Mennonite food, Low German, Russian immigration.
  9. ↑ "Overview cross-cousin". Oxford reference. Retrieved 5 March 2020.
  10. ↑ Starr, Barry (2015-01-13). "How closely related are double cousins?". The Tech Interactive . Retrieved 2024-08-04.
  11. ↑ Quinn, Jillynne (2014-01-09). "How is someone related to the child of their parent's half-sibling?". The Tech Interactive . Retrieved 2024-08-04.
  12. ↑ "Genetic And Quantitative Aspects Of Genealogy - Classification Of Relationships". www.genetic-genealogy.co.uk.
  13. ↑ "part 7 G4BB: World of Tinker-Toys". February 20, 2011.
  14. ↑ "What Is a Step Cousin?". www.reference.com. Ask Media Group, LLC. 4 August 2015.
  15. ↑ "cousin-in-law". Webster's Dictionary.
  16. 1 2 3 "Genetic And Quantitative Aspects Of Genealogy – CALCULATION OF THE COEFFICIENT OF RELATIONSHIP". Genetic-genealogy.co.uk. Retrieved 28 October 2014.
  17. 1 2 Kershaw, Sarah (26 November 2009). "Shaking Off the Shame". The New York Times.
  18. 1 2 Conniff, Richard. "Go Ahead, Kiss Your Cousin". Discover. Kalmbach Media.
  19. ↑ Bittles, Alan H. (May 2001). A Background Summary of Consanguineous Marriage (PDF) (Technical report). Edith Cowan University.
  20. ↑ Bittles, Alan H. (September 1994). "The Role and Significance of Consanguinity as a Demographic Variable". Population and Development Review . 20 (3): 567. doi:10.2307/2137601. JSTOR   2137601.
  21. ↑ Bittles, Alan; Black, Michael (Sep 2009). "Consanguinity, human evolution, and complex diseases". Proceedings of the National Academy of Sciences . 107 (suppl 1): 1779–86. doi: 10.1073/pnas.0906079106 . PMC   2868287 . PMID   19805052.
  22. ↑ Alan Bittles; Michael Black. "Global prevalence". consang.net. Archived from the original on 2016-02-11. Retrieved 2017-11-06.
  23. ↑ Moore, Alexander (1998). Cultural Anthropology: The Field Study of Human Beings. Rowman & Littlefield. p. 216. ISBN   9780939693481.
  24. ↑ "The Surprising Truth About Cousins and Marriage". 14 February 2014.
  25. ↑ Paul, Diane B.; Spencer, Hamish G. (23 December 2008). ""It's Ok, We're Not Cousins by Blood": The Cousin Marriage Controversy in Historical Perspective". PLOS Biology. 6 (12): 2627–30. doi: 10.1371/journal.pbio.0060320 . PMC   2605922 . PMID   19108607.
  26. ↑ "Final Thoughts". Cousin Couples. Retrieved 4 June 2016.
  27. ↑ Brandon Keim (23 December 2008). "Cousin Marriage OK by Science". Wired.
  28. ↑ Saletan, William (10 April 2002). "The Love That Dare Not Speak Its Surname". Slate– via Slate.
  29. ↑ The Conversation: What's the genetic disease risk for children of related couples? Date: September 27, 2012. Source: Tiong Tan, Clinical Geneticist at Victorian Clinical Genetics Services and Researcher in Craniofacial Research, Murdoch Children's Research Institute.
  30. ↑ Helgason, A; Pálsson, S; Gudbjartsson, DF; Kristjánsson, T; Stefánsson, K (2008). "An association between the kinship and fertility of human couples". Science. 319 (5864): 813–6. Bibcode:2008Sci...319..813H. doi:10.1126/science.1150232. PMID   18258915. S2CID   17831162.
  31. ↑ Science Daily: Third Cousins Have Greatest Number Of Offspring, Data From Iceland Shows. Date: February 8, 2008; Source: deCODE genetics.
  32. ↑ Khayat, Abdullah M.; Alshareef, Balsam Ghazi; Alharbi, Sara F.; AlZahrani, Mohammed Mansour; Alshangity, Bashaer Abdulwahab; Tashkandi, Noha Farouk (February 2024). "Consanguineous Marriage and Its Association With Genetic Disorders in Saudi Arabia: A Review". Cureus. 16 (2): e53888. doi: 10.7759/cureus.53888 . ISSN   2168-8184. PMC   10924896 . PMID   38465157.
  33. ↑ Nash, Patrick S (2024-05-31). "The Case for Banning Cousin Marriage". Oxford Journal of Law and Religion. doi:10.1093/ojlr/rwae014. ISSN   2047-0770.
  34. ↑ Sarkar, Sonia (2024-11-05). "Young Pakistanis are moving away from cousin marriage owing to the risk of genetic disorders". BMJ. 387: q2181. doi:10.1136/bmj.q2181. ISSN   1756-1833. PMID   39500532.
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