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Intrafamilial marriage could place your child at risk


  • Marrying within a family results in a higher risk of recessive genetic disorders, while any intelligence irregularities are also more likely to be pronounced due to the resulting reduced genetic variety from which the successful genes can evolve.
  • Generally, couples carry a 3% risk of having a child with birth defects. However, this number increases two-folds to 6% where the kinship of the parents is close. Hence, careful family planning is essential if parents wish to give birth to a healthy baby.


If Daenerys Targaryen, Mother of Dragons, were to have a child with Jon Snow, would their child be born with birth defects because the two are related?

From studies into the theory of inbreeding, or intrafamilial marriage, it has been found that there are 2 main consequences regarding the resulting offspring:

  1. It can cause recessive genes – both positive and negative – to become more pronounced, for instance, irregularities affecting intelligence, physical genetic disorders, or disorders that can affect the lifespan of that child, similar to those which occur when parents are unrelated, such as hemophilia, thalassemia, dwarfism and muscle weakness additional information
  2. A lack of genetic variety meaning offsprings are overly similar to their parents and therefore unable to respond to environmental changes as well as their peers. These characteristics result in a greater risk of extinction due to the lack of evolution occurring through the generations, according to the key principles found in the theory of natural selection.

When inquiring as to whether such irregularities occur with every intrafamilial marriage, the answer is that the risks are much greater than in non-kinship marriages. For example, regular marriages carry a 3% risk of offspring being born with an abnormality. However, this number is doubled for marriages of people who are related to one another, meaning a risk level of 6%.

So, going back to the question of whether unrelated married couples are also at risk of giving birth to a child with a genetic disorder –  the answer is yes, should the mother or father already carry those defective genes. Nevertheless, prospective parents can undergo genetic screening to identify the presence of such genes prior to conception.

Through next generation sequencing (NGS), we can currently identify and prevent against the occurrence of genetic disorders with family planning in consultation with genetic specialists who can identify the risk of genetically transferring disorders. This method of screening allows for the rapid and accurate screening of high sensitivity genetic mutations in DNA to provide a risk analysis for any offspring. It also enables couples to make plans to ensure the health and safety of their child, whether that couple is related or not.

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Assist.Prof. Objoon Trachoo, M.D. Summary: Internal Medicine Internal Medicine