Can Double Cousins Marry Each Other? | Genetics Ancestry

Double First Cousin

In a situation where siblings intermarry with another set of siblings, it will result in a rare connection between the families that are involved. The special set of cousins that are produced through the union is known as double cousins. Are double cousins genetically half-cousins? The answer to that question is yes. We shall be giving definite answers to what it means to be a double cousin and several others related to this topic in this article.

What is a Double Cousin?

What does double first cousin mean? Double cousins share the same set of grandparents. They are first cousins but twice. When two siblings meet and have children for two other siblings, the situation of double cousins will be arrived at. Double cousins share both sides of their paternal and maternal families. They, therefore, share two sets of grandparents instead of only one. They are genetically twice more twice more ancestors in common because their double cousin DNA is 25%. 

what is double first cousin

Double first cousins DNA are more genetically related than first cousins. The scenario is more pronounced when we compare the DNA gotten from their fathers against that taken from their mothers. Double cousin DNA is the same that is shared with an aunt or uncle, half-sibling, or grandparent.  The offspring of double first cousins are double second cousins. 

If you critically look into your family tree, it will be easy to trace double cousins there. You may be a double cousin to some of your relatives. A look at the statistics shows many types of double cousins, the most popular among the lot is double first cousins because the attention and focus on it is huge. They are very common in years gone bye but are few in their numbers in this present dispensation. 

Your take might be locating your double first cousin within your family tree, or you might discover that you are indeed the double cousin yourself; all the tools that you will need to get the right results are delivered in this article. 

How Closely related are Double First Cousins?

The double first cousins’ relationship is not the same as what exists between first cousins. They are twice as related and share the common traits of their four grandparents and go on to share 100% of their ancestors. It is over 50% of what most cousins share. The scenario described here is double first cousins explained in full detail. They have a strong affinity with their most recent grandparents and the connection with both sides of their families is super strong. 

Did you know that when we examine the narratives of Biblical ancestors, instances of intermarriage within their family tree can be observed? Genetics Ancestry provides comprehensive information about DNA, Ethnicity, and Ancestry.

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Double First Cousins are Common

How rare are double first cousins? They are in no way rare but are indeed very common. They happen in varying scenarios. The reason for this lies in the fact they are born in small areas or small towns. On some occasions, they are born into an endogamous population. Nowadays with technological development and the widening of the means of transportation across the world, getting first cousins in closely knitted areas is not very common. This is because the movement of people from one place to the other is now more pronounced because of the ease of transportation.


Our take on the DNA of Double First Cousins

Double cousin DNA percentage share double the percentage of DNA seen in first cousins. Taking a look at the DNA shared by two first cousins, the average is 12.5%. With double first cousins, however, the average is 25% of DNA.  This figure is in line with what is obtainable with half-siblings. The available statistics show that double first cousins share the exact amount of DNA as half-siblings. This is in no way proving that the two are the same; it only shows that they are having more genetics in common than what is obtainable through the regular first cousins. 

The Double cousin DNA percentage will be close to that of half-siblings. Their descendants from the first through to the fourth generation will have a closer genetic affiliation than what is obtainable through cousins of the same relationship. 

Can Double Cousins Marry Each Other?

The legality and advisability of double cousins marrying each other varies depending on location and individual circumstances. Here’s a breakdown:

  • Legality: In most countries, there are no laws prohibiting marriage between double cousins. It’s generally considered legal.

  • Risk Factors: There’s a slightly increased risk of having children with recessive genetic disorders when parents are close relatives like double cousins. This is because they share more genes than unrelated couples. However, the overall risk increase is relatively small (around 1-2%).

  • Genetic Counseling: If you’re considering marriage as double cousins, consulting a genetic counselor is recommended. They can assess your family history for any known genetic risks and provide more specific information about potential risks for your children.

  • Social and Cultural Factors: In some cultures, marriage between close relatives may be frowned upon or even taboo. It’s important to consider any social or cultural factors that might be relevant to your situation.

Understanding double first cousin really helps you to understand the relations also while Many people use suffixes in their names so you can also learn about suffixes here.

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Double Cousins – Are they Genetically Siblings?   

 Are they genetically siblings? The candid answer to that is no. The fact that they share the same amount of DNA in line with what is seen in half siblings, does not make them genetic siblings.  For the statement to be true, there is the need for them to share the same parent/parents.  The double first cousin represents children of couples that are from different family backgrounds; they are therefore not in the category of people that can be referred to as siblings. 

Double First Cousin Family Tree Example

We can get a clearer understanding of this topic by looking at the family tree. Double first cousins have been explained in different forms above; to get a clearer understanding, we are going to look at the family tree. Let us take a look at the figurative expression of the family tree below:

Double First Cousin Family Tree Example


What are examples of double cousins? Assume you meet a great damsel that has an equally great sister and you wish to introduce her sister to your brother; when the lines fall in place and there is a meeting point; marriage will take place. The off-spring that will come out of the union are double first cousins. 

How can you know the Amount of DNA that you share with your Cousin?

What happens when double first cousins have a child? If the parents of double cousins are identical twins, they can be genetic siblings. Knowing how much DNA you share is not possible. However, if you take a DNA test like CRI genetics, it will reveal the amount of DNA that you have in common. 

However, if you want to discover your exact relationship, clinical results can be achieved through CRI paternity. Both CRI Genetics and CRI Paternity use the same tools that complement each other.  It makes it possible for users to widen the scope of knowledge of their origin and discover the most accurate answer moving forward.  

In the tapestry of kin, how’s my great uncle’s son intertwined with me? Indeed, we hold the answer! Genetics Ancestry possesses boundless knowledge, unraveling the threads of ancestry with clarity.

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When Both Parents are Twins

The nature of the twin’s parents will determine what makes a double first cousin. If the twin parents come from two different eggs, they are fraternal twins. They are siblings born on the same day and share about 60% of their DNA. They are going to share about 25% of their DNA. The DNA of identical twins rarely varies. They are the exact clones of each other. The mark of distinction that can be used to separate them from each other is not more than beauty marks. Double first cousin marriage birth defects will reflect in the body of their siblings.

When twin brothers reproduce with twin sisters, their siblings will be genetically indistinguishable from grown-up siblings. When two sets of identical twins give birth to children, their offspring have more in common than half-siblings but are not less related when they become full-grown siblings. The DNA shared by the offspring of identical twins is between 25% – 50% of DNA.  

double first cousin

The difference between Double Cousin, Half Cousin, and double Second Cousin

The DNA similarity between double first cousins brings about the double first cousin marriage birth defects that affect the offspring of the union. In the case of double cousins, the situation will arise when two siblings from one family marry two siblings from another family. The product of the marriage automatically becomes double first cousins. They share both sets of grandparents and are related as half-siblings.

The first cousins share about 1/8, or 12.5% of DNA, while double cousins share around 1/4, or 25% of DNA. The word double is used because twice the DNA relative to the first cousin is shared.  Just as is the case with half-siblings, the double cousins share 25% of DNA.

On the part of a half-cousin, they are cousins from half-siblings. The word average is used because the genetic composition is 1/16, or 6.25% of DNA. This is half the amount that will be seen with first cousins that are regarded as standard. The children of double cousins are referred to as double second cousins. They are related because of their genetic composition. They share between themselves 12.5% DNA.

If you want to completely understand the scope of a cousin relationship, then you must understand the amount of DNA that is shared between cousins.

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Final thoughts

We have been able to dwell extensively on the subject matter of double first cousins. In this article, double first-cousin marriage birth defects have been analyzed. It is clear from our arguments above that double first cousins share the same grandparents. If you want to locate your double first cousin, then you can search for it online in the same way you will search for your DNA through DNA testing. When parents become more curious about their siblings; they will discover more about a double first cousin DNA in their lineage.

Unraveling your heritage, a task not arduous in modern days, Where one’s very image, in a photo, conveys ancestral ways… 

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How are double first cousins related genetically?

Double first cousins share a higher percentage of their DNA than regular cousins, making their genetic relationship stronger.

What’s the distinction between “double” and “first” cousins?

“Double” refers to the sharing of both sets of grandparents, and “first” indicates that the common ancestors are the closest generation back.

Do double first cousins resemble each other more than regular cousins?

Double first cousins might share more physical and genetic similarities due to their stronger genetic connection.

Is the concept of double first cousins common worldwide?

The concept exists in various cultures, but it’s not as common as regular cousin relationships.

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