Editing Incest (section)

==Types==

===Between adults and children===
{{Main|Child sexual abuse}}

Sex between an adult family member and a child is usually considered a form of child sexual abuse,<ref>{{Cite journal |last=Fridell |first=Lorie A. |title=Decision-making of the District Attorney: diverting or prosecuting intrafamilial child sexual abuse offenders |journal=[[Criminal Justice Policy Review]] |volume=4 |issue=3 |pages=249–267 |doi=10.1177/088740349000400304 |date=October 1990 |s2cid=145654768 }}</ref> also known as '''child incestuous abuse''',<ref>{{cite web |last=Trusiani|first=Jessica|title=Working with Survivors of Child Incestuous Abuse |website=Rutgers School of Social Work |url=http://socialwork.rutgers.edu/Libraries/VAWC/Trusiani_presentation.sflb.ashx|archive-url=https://web.archive.org/web/20141101063712/http://socialwork.rutgers.edu/Libraries/VAWC/Trusiani_presentation.sflb.ashx|archive-date=1 November 2014}}</ref> and for many years has been the most reported form of incest. Father–daughter and stepfather–stepdaughter sex are the most commonly reported forms of adult–child incest, with most of the remaining involving a mother or stepmother.<ref name=Turner>{{cite book |title=Encyclopedia of Relationships Across the Lifespan |last=Turner |first=Jeffrey S. |year=1996 |publisher=Greenwood Publishing Group |page=[https://archive.org/details/encyclopediaofre0000turn/page/92 92] |isbn=978-0-313-29576-8 |url=https://archive.org/details/encyclopediaofre0000turn/page/92 }}</ref> Many studies found that stepfathers tend to be far more likely than biological fathers to engage in this form of incest. One study of adult women in San Francisco estimated that 17% of women were abused by stepfathers and 2% were abused by biological fathers.<ref>{{cite book |last=Kinnear |first=Karen L. |title=Childhood Sexual Abuse: A Reference Handbook |page=8}}</ref> Father–son incest is reported less often, but it is not known how close the frequency is to heterosexual incest because it is probably more under-reported.<ref>{{Cite journal |doi=10.1007/BF00754448|title=Father-son incest: A review and analysis of reported incidents|journal=Clinical Social Work Journal|volume=16|issue=2|pages=165–179|year=1988|last1=Williams|first1=Mark|s2cid=144258944}}</ref><ref>{{Cite journal |doi=10.1176/ajp.135.7.835|pmid=665796|title=Father-son incest: Underreported psychiatric problem?|journal=American Journal of Psychiatry|volume=135|issue=7|pages=835–838|year=1978|hdl=1811/51174|last1=Dixon|first1=K. N.|last2=Arnold|first2=L. E.|last3=Calestro|first3=K.|citeseerx=10.1.1.1018.8536}}</ref><ref>{{cite book |title=Don't Tell: The Sexual Abuse of Boys |first=Michel |last=Dorais |translator=Isabel Denholm Meyer |year=2002 |page=24 |publisher=McGill-Queen's Press |isbn=978-0-7735-2261-9}}</ref><ref>{{cite book |title=Healing the Incest Wound: Adult Survivors in Therapy |first=Christine A. |last=Courtois |year=1988 |publisher=W. W. Norton & Company |isbn=978-0-393-31356-7}}</ref> The prevalence of incest between parents and their children is difficult to estimate due to secrecy and privacy.

In a 1999 news story, the [[BBC]] reported: "Close-knit family life in India masks an alarming amount of sexual abuse of children and teenage girls by family members, a new report suggests. Delhi organisation [[RAHI Foundation|RAHI]] said 76% of respondents to its survey had been abused when they were children{{nbsp}}{{ndash}} 40% of those by a family member."<ref>{{Cite news |last=Lak |first=Daniel |date=22 January 1999 |title=India's hidden incest |url=http://news.bbc.co.uk/2/hi/south_asia/259959.stm |work=BBC News}}</ref>

According to the National Center for Victims of Crime a large proportion of [[rape]] committed in the United States is perpetrated by a family member:
{{blockquote|1=Research indicates that 46% of children who are raped are victims of family members (Langan and Harlow, 1994). The majority of American rape victims (61%) are raped before the age of 18; furthermore, 29% of all rapes occurred when the victim was less than 11 years old. 11% of rape victims are raped by their fathers or stepfathers, and another 16% are raped by other relatives.<ref>{{cite web|url=http://www.ncvc.org/ncvc/main.aspx?dbName=DocumentViewer&DocumentID=32360|title=Incest|work=National Center for Victims of Crime and Crime Victims Research and Treatment Center|year=1992|publisher=National Center for Victims of Crime|access-date=27 March 2008|archive-date=10 August 2020|archive-url=https://web.archive.org/web/20200810214920/http://www.ncvc.org/ncvc/main.aspx?dbName=DocumentViewer&DocumentID=32360|url-status=dead}}</ref>}}

Adults who as children were incestuously victimized by adults often suffer from low [[self-esteem]], difficulties in interpersonal relationships, and [[sexual dysfunction]], and are at an extremely high risk of many mental disorders, including [[Clinical depression|depression]], [[anxiety disorder]]s, [[Phobia|phobic avoidance reactions]], [[somatoform disorder]], [[substance abuse]], [[borderline personality disorder]], and [[complex post-traumatic stress disorder]].<ref name="Courtois" /><ref>{{cite book |last2=Barrett |first2=Mary Jo |title=Systemic Treatment of Incest: A Therapeutic Handbook |last1=Trepper |first1=Terry S. |publisher=Psychology Press |year=1989 |isbn=978-0-87630-560-7}}</ref><ref>{{cite book |title=Incest-Related Syndromes of Adult Psychopathology |first=Richard P. |last=Kluft |year=1990 |publisher=American Psychiatric Pub, Inc. |pages=83, 89 |isbn=978-0-88048-160-1}}</ref>

The [[Goler clan]] in [[Nova Scotia]] is a specific instance in which child sexual abuse in the form of forced adult{{ndash}}child and sibling{{ndash}}sibling incest took place over at least three generations.<ref name="cruise">{{Cite book |title=On South Mountain: The Dark Secrets of the Goler Clan |last1=Cruise |first1=David |last2=Griffiths |first2=Alison |publisher=Penguin Books |year=1998 |isbn=978-0-670-87388-3}}</ref> A number of Goler children were victims of sexual abuse at the hands of fathers, mothers, uncles, aunts, sisters, brothers, cousins, and each other. During interrogation by police, several of the adults openly admitted to engaging in many forms of sexual activity, up to and including full intercourse, multiple times with the children. Sixteen adults (both men and women) were charged with hundreds of allegations of incest and sexual abuse of children as young as five.<ref name="cruise" /> In July 2012, twelve children were removed from the [[Colt clan incest case|'Colt' family]] (a pseudonym) in [[New South Wales]], Australia, after the discovery of four generations of incest.<ref name=ccnsw>{{cite web|url=http://www.caselaw.nsw.gov.au/action/PJUDG?jgmtid=167373 |title=DFaCS (NSW) and the Colt Children [2013] NSWChC 5 |publisher=Children's Court, New South Wales |date=13 September 2013 |archive-url=https://web.archive.org/web/20131217044158/http://www.caselaw.nsw.gov.au/action/PJUDG?jgmtid=167373 |archive-date=17 December 2013 }}</ref><ref name=nca131210>{{cite news |url=http://www.news.com.au/lifestyle/real-life/the-case-of-incest-and-depravity-which-came-to-rest-in-the-hills-of-a-quiet-country-town/story-fnixwvgh-1226780575248 |title=The case of incest and depravity which came to rest in the hills of a quiet country town |first=Candace |last=Sutton |work=[[News Corp Australia]] |date=10 December 2013 |access-date=14 December 2013 |archive-date=8 November 2016 |archive-url=https://web.archive.org/web/20161108041054/http://www.news.com.au/lifestyle/real-life/the-case-of-incest-and-depravity-which-came-to-rest-in-the-hills-of-a-quiet-country-town/story-fnixwvgh-1226780575248 }}</ref> Child protection workers and psychologists said interviews with the children indicated "a virtual sexual free-for-all".<ref name=nca131212>{{cite news |url=http://www.news.com.au/national/nsw-act/the-family-tree-of-the-depraved-family-who-live-in-the-hills-of-a-quiet-country-town/story-fnii5s3x-1226781805877 |title=The family tree of the depraved family who live in the hills of a quiet country town |first=Candace |last=Sutton |work=[[News Corp Australia]] |date=12 December 2013 |access-date=14 December 2013 |archive-date=25 September 2016 |archive-url=https://web.archive.org/web/20160925061616/http://www.news.com.au/national/nsw-act/the-family-tree-of-the-depraved-family-who-live-in-the-hills-of-a-quiet-country-town/story-fnii5s3x-1226781805877 }}</ref>

While incest between adults and children generally involves the adult as the perpetrator of abuse, there are rare instances of sons sexually assaulting their mothers. These sons are typically mid-adolescent to young adult, and, unlike parent-initiated incest, the incidents involve some kind of physical force. Although the mothers may be accused of being seductive with their sons and inviting the sexual contact, this is contrary to evidence.<ref name="Courtois 2">{{cite book |last=Courtois |first=Christine  |title=Healing the Incest Wound: Adult Survivors in Therapy |year=2010 |publisher=W. W. Norton & Company |isbn=978-0-39370-547-8 |pages=71–72 }}</ref><ref name="Ward">{{cite book |last=Ward |first=Elizabeth  |title=Father-Daughter Rape |year=1985 |publisher=W. W. Norton & Company |isbn=978-0-39462-032-9 }}</ref> Such accusations can parallel other forms of rape, where, due to [[victim blaming]], a woman is accused of being at fault for the rape. In some cases, mother–son incest is best classified as [[acquaintance rape]] of the mother by the adolescent son.<ref name="Courtois 2"/><ref name="Ward"/>

===Between children===
Childhood [[Sibling incest|sibling–sibling incest]] is considered to be widespread but rarely reported.<ref name=Turner /> Sibling–sibling incest becomes [[child-on-child sexual abuse]] when it occurs without consent, without equality, or as a result of [[coercion]]. In this form, it is believed to be the most common form of intrafamilial abuse.<ref>{{cite book |last=Kalogerakis |first=Michael G. |author2=American Psychiatric Association. Workgroup on Psychiatric Practice in the Juvenile Court |title=Handbook of psychiatric practice in the juvenile court: the Workgroup on Psychiatric Practice in the Juvenile Court of the American Psychiatric Association |year=1992 |publisher=American Psychiatric Pub |isbn=978-0-89042-233-5 |page=106 |url=https://books.google.com/books?id=nsUloUgZwRoC&pg=PA106 }}</ref> The most commonly reported form of abusive sibling incest is abuse of a younger sibling by an older sibling.<ref name=Turner />

[[Sibling abuse#Sexual abuse|Sibling abusive incest]] is most prevalent in families where one or both parents are often absent or emotionally unavailable, with the abusive siblings using incest as a way to assert their power over a weaker sibling.<ref name=leder>{{cite news|last=Leder |first=Jane Mersky |title=Adult Sibling Rivalry: Sibling rivalry often lingers through adulthood |url=https://www.psychologytoday.com/us/articles/199301/adult-sibling-rivalry |work=Psychology Today |volume=January/February 93 |publisher=Sussex Publishers }}</ref> Absence of the father in particular has been found to be a significant element of most cases of sexual abuse of female children by a brother.<ref name=rudd>{{cite journal |last1=Rudd |first1=Jane M. |last2=Herzberger |first2=Sharon D. |title=Brother-sister incest—father-daughter incest: a comparison of characteristics and consequences |journal=Child Abuse & Neglect |volume=23 |issue=9 |date=September 1999 |pages=915–928 |doi=10.1016/S0145-2134(99)00058-7 |pmid=10505905}}</ref> 

===Between adults===
Proponents of incest between consenting adults draw clear boundaries between the behavior of consenting adults on one hand and rape, child molestation, and abusive incest on the other.<ref name="guardian2002">{{cite news |last=Hari |first=Johann |date=9 January 2002 |title=Forbidden love |url=https://www.theguardian.com/Archive/Article/0,4273,4331603,00.html |access-date=11 April 2008 |newspaper=[[The Guardian]] |issn=0261-3077}}</ref> However, even consensual relationships such as these are still legally classified as incest<ref>{{cite book |author=Roffee |first=James |title=Rape Justice: Beyond the Criminal Law |year=2015 |isbn=9781137476159 |pages=72–91 |chapter=When Yes Actually Means Yes |doi=10.1057/9781137476159_5}}</ref> and criminalized in many jurisdictions (although there are [[Legality of incest|certain exceptions]]). James Roffee, a senior lecturer in criminology at [[Monash University]] and former worker on legal responses to familial sexual activity in England and Wales, and Scotland<ref>{{cite web|url=http://monash.edu/research/explore/en/persons/james-roffee(896c15d7-6f28-4bf0-8a0f-b7d6ff1553e0).html|title=Dr James Roffee|publisher=Monash university|access-date=22 May 2017|archive-url=https://web.archive.org/web/20170204003059/http://monash.edu/research/explore/en/persons/james-roffee%28896c15d7-6f28-4bf0-8a0f-b7d6ff1553e0%29.html|archive-date=4 February 2017}}</ref> discussed how the [[European Convention on Human Rights]] deems all familial sexual acts to be criminal, even if all parties give their full consent and are knowledgeable to all possible consequences.<ref>{{cite journal|doi=10.1093/hrlr/ngu023|title=No Consensus on Incest? Criminalisation and Compatibility with the European Convention on Human Rights|journal=Human Rights Law Review|volume=14|issue=3|pages=541–572|year=2014|last1=Roffee|first1=J. A.}}</ref> He also argues that the use of particular language tools in the legislation manipulates the reader to deem all familial sexual activities as immoral and criminal, even if all parties are consenting adults.<ref>{{cite journal |author=Roffee |first=J.A. |year=2014 |title=Synthetic Necessary Truth Behind New Labour's Criminalisation of Incest |journal=Social & Legal Studies |volume=23 |pages=113–130 |doi=10.1177/0964663913502068 |s2cid=145292798}}</ref>
====Aunts, uncles, moms, dads, nieces or nephews====
{{see also|Avunculate marriage}}
In the [[Netherlands]], marrying one's nephew or niece is legal, but only with the explicit permission of the Dutch government, due to the possible risk of [[genetic defects]] among the offspring. Nephew-niece marriages predominantly occur among foreign immigrants. In November 2008, the Scientific Institute of the Christian Democratic Party (CDA) announced that it wanted a ban on marriages to nephews and nieces.<ref>{{cite web|url=http://gatesofvienna.blogspot.com/2008/11/gates-of-vienna-news-feed-11262008.html|title=Gates of Vienna News Feed 11/26/2008|first=Baron|last=Bodissey|date=26 November 2008}}</ref> Consensual sex between individuals aged 18 and older is always lawful in the Netherlands and Belgium, even among closely related family members. Sexual acts between an adult family member and a minor are illegal, though they are classified not as incest but as abuse of the authority such an adult has over a minor, comparable to that of a teacher, coach, or priest.<ref>{{cite web|url=http://www.elfri.be/incest-strafbaar |title=is incest strafbaar ? &#124; Goede raad is goud waard – Advocatenkantoor Elfri De Neve |publisher=Elfri.be |date=15 July 2009 |access-date=30 July 2013|language=nl}}</ref> In [[Florida]], consensual adult sexual intercourse with someone known to be one's aunt, uncle, niece, or nephew constitutes a felony of the third degree.<ref>Criminal Law – Page 200, John M. Scheb – 2008</ref> Other states also commonly prohibit marriages between such kin.<ref>Family Law in the USA – Page 207, Lynn Dennis Wardle, Laurence C. Nolan – 2011</ref> The legality of sex with a half-aunt or half-uncle varies state by state.<ref>The Encyclopedia of Genetic Disorders and Birth Defects – Page 101, James Wynbrandt, Mark D. Ludman – 2010</ref> In the United Kingdom, incest includes only sexual intercourse with a parent, grandparent, child, or sibling,<ref>{{cite web|title=Incest by a man.|url=http://www.legislation.gov.uk/ukpga/Eliz2/4-5/69/part/I/crossheading/incest|work=Sexual Offences Act 1956|publisher=National Archives UK|access-date=28 March 2014}}</ref> but the more recently introduced offense of "sex with an adult relative" extends as far as half-siblings, uncles, aunts, nephews, and nieces.<ref name=ref1>{{cite web|title=Sexual Offences Act 2003|url=http://www.legislation.gov.uk/ukpga/2003/42/section/64|work=legislation.gov.uk|publisher=The National Archives of United Kingdom|access-date=28 March 2014}}</ref> However, the term 'incest' remains widely used in popular culture to describe any form of sexual activity with a relative. In Canada, marriage between uncles and nieces and between aunts and nephews is illegal.{{Citation needed|date=April 2025}}

====Between adult siblings====
{{main|Sibling incest}}

One of the most public cases of adult sibling incest in the 2000s is the case of [[Cases of Stübing v. Germany|Patrick Stübing and Susan Karolewski]], a brother{{ndash}}sister couple from Germany. Because of violent behavior on the part of his father, Patrick was taken in at the age of 3 by foster parents, who adopted him later. At the age of 23 he learned about his biological parents, contacted his mother, and met her and his then 16-year-old sister Susan for the first time. The now-adult Patrick moved in with his birth family shortly thereafter. After their mother died suddenly six months later, the siblings became intimately close, and had their first child together in 2001. By 2004, they had had four children together: Eric, Sarah, Nancy, and Sofia. The public nature of their relationship, and the repeated [[prosecution]]s and jail time they have served as a result, have caused some in Germany to question whether incest between consenting adults should be punished at all. An article about them in ''[[Der Spiegel]]'' states that the couple are happy together. According to court records, the first three children have mental and physical disabilities, and have been placed in foster care.<ref name="spiegel" /> In April 2012, at the [[European Court of Human Rights]], Patrick Stübing lost his case that the conviction violated his right to a private and family life.<ref>{{cite web|url=http://www.cnn.com/2012/04/13/world/europe/germany-incest-court/index.html?hpt=hp_bn2|title=German incest couple lose European court case |website=[[CNN]]|date=13 April 2012}}</ref><ref name="ECtHR judgment">[http://cmiskp.echr.coe.int/tkp197/view.asp?action=html&documentId=905957&portal=hbkm&table=F69A27FD8FB86142BF01C1166DEA398649 Judgment] on the ''Stübing vs. Germany'' case. [[European Court of Human Rights]].</ref> On 24 September 2014, the [[German Ethics Council]] recommended that the government abolish laws criminalizing incest between siblings, arguing that such bans impinge upon citizens.<ref>{{cite web|url=http://www.thedailybeast.com/cheats/2014/09/24/german-ethics-council-incest-is-a-right.html |title=German Ethics Council: Incest Is a Right |website=The Daily Beast |date=24 September 2014 |access-date=5 October 2014}}</ref><ref>{{cite news|url=https://www.telegraph.co.uk/news/worldnews/europe/germany/11119062/Incest-a-fundamental-right-German-committee-says.html |archive-url=https://ghostarchive.org/archive/20220111/https://www.telegraph.co.uk/news/worldnews/europe/germany/11119062/Incest-a-fundamental-right-German-committee-says.html |archive-date=11 January 2022 |url-access=subscription |url-status=live |title=Incest a 'fundamental right', German committee says |newspaper=The Telegraph |date=24 September 2014 |access-date=5 October 2014}}{{cbignore}}</ref>

Some societies differentiate between full-sibling and half-sibling relations.<ref>Roger S. Bagnall, Bruce W. Frier, ''The Demography of Roman Egypt'', 2006, p.128</ref><ref>[[Roy Porter]], [[Mikuláš Teich]], ''Sexual Knowledge, Sexual Science: The History of Attitudes to Sexuality'', 1994, p.239</ref>

====Cousin relationships====
{{See also|Cousin marriage|List of coupled cousins}}
[[File:Incest_World_Wide_Chart_(Borysk5_orig_amended_by_Tyir86_with_title,_legend,_bkrd_color).png|thumb|Legal status of incest, globally]]

Marriages and sexual relationships between first cousins are stigmatized as incest in some cultures, but tolerated in much of the world. Currently, 24 [[US states]] prohibit marriages between first cousins, and another seven permit them only under special circumstances.<ref>Joanna Grossman, [https://supreme.findlaw.com/legal-commentary/should-the-law-be-kinder-to-kissin-cousins.html Should the law be kinder to kissin' cousins?]</ref>
The United Kingdom permits both marriage and sexual relations between first cousins.<ref name=Ref1>{{cite web |last=Boseley |first=Sarah |title=Marriage between first cousins doubles risk of birth defects, say researchers |url=https://www.theguardian.com/science/2013/jul/04/marriage-first-cousins-birth-defects |work=[[The Guardian]] |access-date=28 March 2014 |date=4 July 2013}}</ref>

In some non-Western societies, marriages between close biological relatives account for 20{{ndash}}60% of all marriages.<ref>{{cite web|url=https://www.larasig.com/node/2020|title=Consanguinity Fact Sheet – Debunking Common Myths|access-date=23 December 2017|archive-url=https://web.archive.org/web/20171223160732/https://www.larasig.com/node/2020|archive-date=23 December 2017}}</ref><ref>{{cite book|url=https://books.google.com/books?id=t2XgDgAAQBAJ&q=20+to+60+%25+of+all+marriages+between+close+biological+relatives&pg=PT282|title=Family Law: Theoretical, Comparative, and Social Science Perspectives|first=James|last=Dwyer|date=9 December 2014|publisher=Wolters Kluwer Law & Business|via=Google Books|isbn=9781454831556}}</ref><ref>"In some parts of the world 20–60% of all marriages are between close biological relatives (Bittles, 1998)"
 [https://www.researchgate.net/profile/Alan_Bittles/publication/226985985_Genetic_Counseling_and_Screening_of_Consanguineous_Couples_and_Their_Offspring_Recommendations_of_the_National_Society_of_Genetic_Counselors/links/0c960528ac23292963000000.pdf Genetic Counseling and Screening of Consanguineous Couples and Their Offspring: Recommendations of the National Society of Genetic Counselors]</ref>

First- and second-cousin marriages are rare in Western Europe, North America, and Oceania, accounting for less than 1% of marriages, but reach 9% in South America, East Asia, and South Europe, and about 50% in regions of the Middle East, North Africa, and South Asia.<ref>{{cite journal |doi=10.1016/j.paed.2008.02.008 |title=Consanguinity and child health |url=http://www.channel4.com/microsites/D/Dispatches/when_cousins_marry/cousins_10.pdf |year=2008 |last1=Saggar |first1=A |last2=Bittles |first2=A |journal=Paediatrics and Child Health |volume=18 |issue=5 |pages=244–249}}</ref> Communities such as the Dhond and the [[Bhittani]] of Pakistan clearly prefer marriages between cousins due to the belief they ensure purity of the descent line, provide intimate knowledge of the spouses, and ensure that [[Property|patrimony]] will not pass into the hands of "outsiders".<ref>{{Cite book |title=Encyclopedia of Women & Islamic Cultures: Family, Body, Sexuality and Health |first1=Suad |last1=Joseph |author-link=Suad Joseph |first2=Afsaneh |last2=Najmabadi |author2-link=Afsaneh Najmabadi |publisher=Brill |year=2003 |isbn=978-90-04-12819-4 |page=261 |url=https://books.google.com/books?id=bzXzWgVajnQC}}</ref> [[Parallel and cross cousins|Cross-cousin]] marriages are preferred among the [[Yanomami]] of Brazilian Amazonia, among many other tribal societies identified by anthropologists.
[[File:Cousin_marriage_map_USA.svg|thumb|300x300px|'''Laws regarding first-cousin marriage in the States'''{{legend|#000099|Legal}}{{legend|#0066ff|Allowed with requirements}}{{legend|#ff7777|Banned with exceptions<sup>1</sup>}}{{legend|#FF0000|Statute bans  marriage<sup>1</sup>}}{{legend|#990000|Criminal offense<sup>1</sup>}}
----[[Marriage in the United States#Interjurisdictional recognition|<sup>1</sup> Some states recognize marriages]] performed elsewhere, while other states do not.]]
There are some cultures in Asia which stigmatize cousin marriage, in some instances even marriages between second cousins or more remotely related people. This is notably true in the culture of [[Korea]]. In South Korea, before 1997, two people with the same last name and clan were prohibited from marrying. In light of this law being held unconstitutional, South Korea now only prohibits up to third cousins (see [[Article 809 of the Korean Civil Code]]). [[Hmong people|Hmong]] culture prohibits the marriage of anyone with the same last name{{nbsp}}{{ndash}} to do so would result in being shunned by the entire community, and they are usually stripped of their last name.<ref>{{Cite book|url=https://books.google.com/books?id=kgaGCwAAQBAJ&q=Hmong+culture+prohibits+the+marriage+of+anyone+with+the+same+last+name&pg=PA192|title=Hmong Refugees in the New World: Culture, Community and Opportunity|last=Vang|first=Christopher Thao|date=16 May 2016|publisher=McFarland|isbn=9781476622620}}</ref>

In a review of 48 studies of children parented by cousins, the rate of birth defects was twice that of non-related couples: 4% for cousin couples as opposed to 2% for the general population.<ref>{{cite news |last=Towie |first=Narelle |url=http://www.perthnow.com.au/kissing-cousins-ok/story-fna7dq6e-1111116504749 |title=Most babies born to first-cousins are healthy |newspaper=Perth Now |date=31 May 2008 |access-date=5 January 2012 |archive-url=https://web.archive.org/web/20120202060753/http://www.perthnow.com.au/kissing-cousins-ok/story-fna7dq6e-1111116504749 |archive-date=2 February 2012 }}</ref>

====Defined through marriage====
Some cultures include relatives by marriage in incest prohibitions; these relationships are called [[Affinity (law)|affinity]] rather than [[consanguinity]]. For example, the question of the legality and morality of a widower who wished to marry his [[Deceased Wife's Sister's Marriage Act 1907|deceased wife's sister]] was the subject of long and fierce debate in the [[United Kingdom]] in the 19th century, involving, among others, [[Matthew Boulton]]<ref>{{cite book |last=Pollak |first=Ellen |title=Incest and the English Novel, 1684–1814 |publisher=Johns Hopkins University Press |location=Baltimore MD |year=2003 |page=38 |isbn=978-0-8018-7204-4}}</ref><ref>{{cite book |last=Tann |first=Jennifer |title=Oxford Dictionary of National Biography |publisher=Oxford University Press |location=Oxford, England |date=May 2007 |chapter=Boulton, Matthew (1728–1809)|title-link=Oxford Dictionary of National Biography }}</ref> and [[Charles La Trobe]]. The marriages were entered into in Scotland and Switzerland respectively, where they were legal. In medieval Europe, [[Lateran IV]] ruled that standing as a [[godparent]] to a child also created a bond of affinity; which precluded legal marriage.<ref name="b310">{{cite book | last1=Ferraro | first1=J.M. | last2=Pedersen | first2=F. | title=A Cultural History of Marriage in the Medieval Age | publisher=Bloomsbury Publishing | series=The Cultural Histories Series | year=2021 | isbn=978-1-350-17971-4 | url=https://books.google.com/books?id=bqVQEAAAQBAJ&pg=PA133 | access-date=2024-08-23 | page=133}}</ref> But in other societies, a deceased spouse's sibling was considered the ideal person to marry. The Hebrew Bible forbids a man from marrying his brother's widow with the exception that, if his brother dies childless, the man is required to marry his brother's widow so as to "raise up seed to him".<ref>''Hebrew-English Bible'' {{bibleverse||Deuteronomy|25:5–6|HE}}</ref> Some societies have long practiced [[sororal polygyny]], a form of [[polygamy]] in which a man marries multiple wives who are sisters to each other (though not closely related to him).{{Citation needed|date=April 2025}}

In Islamic law, marriage among close blood relations like parents, stepparents, parents in-law, siblings, stepsiblings, the children of siblings, aunts, and uncles is forbidden, while first or second cousins may marry. Marrying the widow of a brother or the sister of a deceased or divorced wife is also allowed.{{Citation needed|date=April 2025}}