The laws of many jurisdictions void incestuous marriages, even if entered into without awareness of the kinship. If an incestuous relationship is suspected, DNA testing may be used. Some jurisdictions permit offspring of IVF donations access to donation records or to adoption records.
People may be unaware of a kinship relationship between them in a number of circumstances. For example, artificial insemination with an anonymous donated sperm may result in offspring being unaware of any biological relations, such as paternity or half siblings. To reduce the likelihood of accidental incest, fertility clinics usually limit the number of times that a donor's sperm may be used. Some countries have laws limiting the number of children a donor can father, while others limit sperm donations based on family numbers to enable one family to have true siblings.
Accidental incest may also arise in the following situations:
- In 2008, it was reported that a British brother and sister, who were twins separated at birth, married without knowing of their relationship. According to the report, the relationship was discovered soon after their wedding, and the marriage was annulled. The case has raised the issue regarding whether adoptions should be kept secret. Concerns have been raised, however, about whether the story is, in fact, true.
- An engaged couple in South Africa, who had been together for five years and were expecting a child, discovered that they were brother and sister just before their wedding. They were raised separately and met as adults in college. Just before the wedding, their parents met and they came to realize that they were siblings. The couple broke off the relationship after the discovery.
- "Accidental Incest Risk Increases". Edmonton Journal. Boston. Associated Press. 15 March 1979. p. 61. Retrieved 23 March 2011.
- Atallah, Lillian (19 April 1976). "Report From A Test Tube Baby". Ocala Star-Banner. p. 35. Retrieved 23 March 2011.
- Alvarez, Lizette (30 September 2004). "Spreading Scandinavian Genes, Without Viking Boats". The New York Times. Retrieved 23 March 2011.
- Oung, Angelica (11 May 2007). "DOH working on provision to stop accidental incest". The Taipei Times. Taiwan. p. 2. Retrieved 23 March 2011.
- Angelica, Jade Christine. A Moral Emergency: Breaking the Cycle of Child Sexual Abuse. p. 59.
- "Unknowing twins married, lawmaker says". CNN. Retrieved 23 March 2011.
- Sabater, Liza. "Accidental Incest: Twins Separated at Birth Marry". Culture Kitchen. Retrieved 23 March 2011.
- Henley, Jon (15 January 2008). "Did a pair of twins really get married by mistake?". The Guardian. London. Retrieved 3 April 2012.
- Maclean, Stewart (3 November 2011). "Engaged couple discover they are brother and sister when their parents meet just before wedding". Daily Mail. Retrieved 9 November 2011.