Why Cousin marriage (Blood Relation) is discouraged Scientifically?

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Cousin marriage


Marrying someone from a different religion and faith is common in today’s time. Of course not to an extent it should have been. But still, it is and it has some benefits as well that we will be discussing later in this article.

However, in old times people around the world believed in marrying their child within their own community, and relatives and it is even followed now. That’s mostly done because different communities and faith people have different traditions so if someone from the same community gets married then things become more relatable and a better understanding of culture can be shared and vice versa.

Scientific view behind genetics

But do you know marrying with the same blood relation aka cousin can lead to some disaster conditions? It’s been said that you don’t have to be sick in order to pass a genetic disease to your child. 

Now to understand this in detail we will be going a bit into science but it’s worth it.

Every organism that has DNA in its chromosomes has two forms of genes with each gene inherited from the mother and father. Thus usually when there is a presence of a dominant gene (Strong gene) and recessive gene (Weak gene) from each partner then the traits that child will have are from the dominant gene. And the child will be less likely to get affected by recessive traits. This is the case when the partner has no blood relation whatsoever.

First Cousins

First Cousins can be easily understood with the below diagram.

Blood relation First cousin

In simple terms, we can say all the children of your father’s brother and sister if any and all the children of your mother’s brother and sister if any will be your first cousins.

Problem with Cousin Marriage

When two people with blood relations get married then there is a higher similarity in their DNA as well. The similarity of both the people can be as high as 12.5% in the case of first cousins.

And If one partner has some abnormality in the gene then the other will also most likely have the same abnormality in the gene as both partners come from the same gene. This is not the case with marrying anyone outside your relations. And the probability of passing on the abnormality to the child is very high.

Most of the Childbirth defects that we see all around the world are caused by genetic problems. And blood relations and cousin marriage are one of the main causes.

However, it is important to consider that the similarity of genes decreases as it goes toward the second cousin, third cousin.. and after the seventh cousin, it is considered that the gene has no similarity.

Does this problem occur for every Blood-related partner?

No, this problem is not necessarily will occur with every blood relation partner. There are many blood-related couples all around the world that are happy and have healthy children as well.

But the risk of such problems is very high with such couples than with any other couple.

And this is the reason why blood relation marriages are discouraged. And it is also illegal in many places in the world.

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