The Legal and Social Implications of Brothers and Sisters Marriage

Marrying a sibling may seem unfathomable to most people today, but the practice of brothers and sisters marriage has existed in various cultures throughout history.

While permitted in some places, sibling marriage is legally prohibited in most countries now due to concerns about potential genetic disorders. It is also widely viewed as taboo across cultures.

This article will examine the legal prohibitions, consequences, and practical implications associated with brothers and sisters marriage.


Marriage between siblings, also known as consanguineous marriage, has occurred most frequently among royalty and aristocracy in various cultures to keep power and wealth within the family. Examples include ancient Egyptian pharaohs and Incan rulers who sometimes married their sisters. The marriage of half-siblings was also permitted in parts of Asia such as Thailand and Japan until the early 20th century.

Today, brothers and sisters marriage elicits shock and taboo in much of the world. There are legal prohibitions against it in most nations. However, a few places still allow marriage between half-siblings, including Brazil, Malaysia, and parts of Australia. Let’s explore the legal restrictions, potential criminal consequences, and societal perceptions around sibling marriage in most parts of the world now.

Laws explicitly banning the marriage of siblings exist in most countries now. These legal prohibitions are primarily based on concerns about potential genetic problems in children born from closely related parents.

In the United States, marriage between siblings is legally prohibited nationwide. The laws of all 50 states consider marriages within certain degrees of consanguinity to be incestuous and therefore void. These include marriages between siblings, half-siblings, uncles/aunts and nieces/nephews, and first cousins in some states. Attempting such a marriage is legally invalid.

Other nations with legal bans on sibling marriage include China, Russia, India, most parts of Europe and the Middle East. Some exceptions exist, such as certain provinces in Canada that permit uncle-niece marriage. Overall though, brothers and sisters marriage is now universally outlawed and considered a criminal offense in most countries.

Marrying a sibling doesn’t just mean the marriage is considered invalid. In many places, it can actually lead to criminal charges, fines, and even imprisonment. Here are some potential legal consequences:

  • Incest is considered a felony offense punishable by prison time in several U.S. states, including Arizona, Kansas, and Michigan. Sentences can range from months to years if convicted.

  • Attempting to obtain a marriage license with a sibling may lead to being charged with fraud or falsification of records. This can result in fines or jail time in some jurisdictions.

  • Traveling to another jurisdiction specifically to evade laws against sibling marriage may still lead to prosecution in the couple’s home location.

  • Immigration authorities may investigate and even seek to deport immigrant siblings found to be engaged in incestuous marriage.

The consequences can be severe lasting stigma, in addition to fines and imprisonment. These legal penalties reflect societal disgust and rejection of consanguineous relationships in most modern nations.

Practical Implications of Brothers and Sisters Marriage

Aside from legal consequences, there are significant practical implications that emerge from marriages between siblings that impact their daily lives. Here are some major issues siblings who marry would likely face:

  • Social Stigma: There is an enormous stigma now associated with incestuous relationships. A sibling couple would likely face prejudice, judgment, and rejection from society, friends, and colleagues who find their relationship unacceptable.

  • Family Relationship Issues: Marrying a sibling can make normal family relationships very awkward and strained. Parents may feel disgust or shame, and it may impact the couples’ relationships with their children as well.

  • Medical Concerns: Children born to siblings have higher risks of congenital disorders and birth defects. Genetic counselling and testing would be advised for such couples.

  • Housing Difficulties: Renting or buying property together may be challenging if their familial status is revealed and judged negatively. Discrimination from landlords or sellers is possible.

Brothers and sisters who marry could face constant social disapproval, family tensions, medical concerns, and discrimination in their daily lives. These practical issues can make maintaining the marriage very difficult.


In summary, while accepted in ancient royal families, the concept of brothers and sisters marriage is taboo and universally outlawed in the modern era. Legal prohibitions exist in most nations against sibling marriage due to medical concerns over birth defects. Marrying a sibling can also lead to criminal charges and imprisonment in many jurisdictions. Beyond legal consequences, tremendous social stigma and family relationship problems often arise from such unions.

Practical obstacles like discrimination and medical risks would also confront couples in consanguineous marriages daily. Overall, while the practice has persisted in small pockets, it is now widely discouraged and banned legally and socially in most of the world. The potential genetic risks to offspring combined with societal taboos make brothers and sisters marriage legally and practically unviable in most countries today.