Is There a Country Where You Can Marry Your Sibling?

There is a country where you can marry your sibling, and in fact, there are a few.

The countries where you can marry your sibling under certain circumstances are Argentina, Brazil, Thailand, and the Netherlands, with some exceptions in the laws of those two last countries.

Yes, you can marry your siblings in some countries. It is permitted in Argentina, Brazil, Thailand, and the Netherlands under certain circumstances.

Most laws that pertain to the marriage of siblings make provisions for what is acceptable, and frequently connect those exceptions to laws connected to incest.

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Are incest and sibling marriage connected?

incest and sibling marriage

There is no law that says marriage to a sibling and incest are connected, but incest is clearly defined in almost every country.

The most common definition of incest is that it is sexual activity between family members or relatives that are close to the bloodline.

This, by reasonable implication, would make marriage an incestuous act if siblings consummated the marriage.

Still, if marriage to a sibling is legal then, reasonably, that would suggest that incest, in some senses, is legal. In a few countries, it is not criminalized in certain circumstances.

In most countries, particularly developed countries, incest is illegal and/or criminalized with punitive consequences.

There are some countries that make incest illegal, but they do not have laws that make sexual relationships between same-sex couples illegal.

Then there are countries that consider incest socially unreasonable and unethical, but it is not criminalized – making it legal.

Other countries do not allow incest between minors but will allow for marriages within the same family lines between two consenting adults.

How is marriage between siblings defined in the law?

 identical twins

In places where a marriage between siblings is legal, marriage is defined in the law by a definition known as consanguinity, and also by the nature of the family relationship between the two parties.

Those two variables are one and the same, and not every law pertaining to this subject uses the term consanguinity, although many do.

The term consanguinity applies to the percentage of DNA shared between two parties.

So, for example, a pair of identical twins would have 100 percent DNA. When you see laws pertaining to marriage between siblings, the laws often accept marriages when this percentage is low, or when the nature of the family relationship between the two parties is rather distant.

There are also countries where marriage between siblings is permitted when the sibling relationship isn’t known by either party or, one of the parties is adopted.

Consanguinity is determined by calculating generations and how close that number connects to the common ancestor between the parties, with the prohibition of marriage occurring at 25 percent.

So, two siblings with the same mother and father would have a level of consanguinity that wasn’t provided for by the law for marriage, in most countries, as their level of consanguinity would be 37.5 percent.

Where you see exceptions and circumstances for marriage by siblings most often is when the nature of their family relationship is distant or unknown.

Incest is legal in some countries, but sex with minors of any relationship is not legal in any country and is defined by every international agency as sexual child abuse.

It is important to note that many countries allow for marriage at the ages of 12 and 14.

Is incest legal

The countries that are said to look the other way on many forms of incest are Latvia, Belgium, Turkey, South Korea, Russia, Portugal, China, Belgium, Japan, Spain, and France.

Each of these countries that permit this has a law that defines what is okay and what is not, with incest being defined as sexual relationships between family members.

Relationships between parent and child would be forbidden, but with distant relatives, it might not be.

It is also worth noting that many countries that permit incestuous relationships by law do not permit marriage between relatives.

There are also countries that do not define incest at all. In India for example, it is not defined, but it could be considered exploitation if a report was filed on the matter.

Other countries do not criminalize incest in the way of punitive consequences and may simply fine or socially reprimand anyone that engages in this.

Legal to Marry

It is legal to marry a sibling in Argentina. Here, the parties must be over the age of consent, which is 18.

Marriage between an ascendant and a descendant is illegal and would be invalidated. Brazil has no punishment for relations between people over the age of 14.

Brazil law also allows for marriages between first cousins, and marriages between other family relationships are considered invalid.

That means that the parties involved will not be punished for their relationships beyond having their relationship invalidated by law.

Some countries that have exceptions to the law make these determinations on the grounds that marriage is a family relationship.

The consensus is that invalidating an existing marriage between family members is not changing the nature of the relationship, just the legality of it, and the principle of consanguinity is used here.

Brazilian law actually specifies in Article 1521 of their Civil Code that parents and their children (a relationship with consanguinity of 50 percent), and grandparents and their grandchildren would have their marriages invalidated.

Brazil does allow for marriages between parties where the consanguinity is 25 percent (such as with half-siblings), and permission will be issued upon a health check.

What countries have exceptions when it comes to marrying siblings?


The countries that have exceptions when it comes to marrying siblings are Thailand, Latvia, and the Netherlands.

These countries have exceptions similar to Brazil’s where the principle of consanguinity applies.

In Thailand, incest between parties over the age of 15 is not illegal. Marriage is not illegal either unless one party is a direct descendant of the other.

In Thailand also, siblings cannot be full or half-siblings but can be stepsiblings or adopted siblings.

Latvia also has not prohibited incest but only incest between minors. The same applies to the Netherlands.

Marriage is forbidden between direct ascendants and descendants, and siblings cannot marry.

There are circumstances where siblings can apply to the Minister of Justice for an exception to the rule, and these are typically granted in the case of adoptions or stepsiblings, or in third and fourth-degree sibling relationships when both have declared consent.

What do you think of a marriage between siblings?

There are many reasons why countries would permit the sealing of a relationship between siblings, whether they are in the same bloodline or not.

For some developing countries, the law pertains to social and economic needs, and often property values and territory are included in marriages.

For this reason, a marriage between siblings of any kind may be performed to protect family lineage and inheritance, as opposed to protecting a romantic relationship.

For relationships like this, incest and marriage may not even be connected, and the incest may never occur, but it could if producing more lineage is a requirement of the country or parties.

Developed countries have a clear no on every angle of this form of relationship but look poorly at the idea of incest and sibling marriages.

What do you think of a marriage between siblings?