Queens and Genes: The Dangers of Royal Inbreeding

Love them or hate them, royal families have a fascinating history. From the Egyptian Pharaohs to Queen Elizabeth II, there have been many monarchs across many continents and many years. Historically, one family would manage to stay in power through consanguinity, marrying a biological relative. The theory was that marrying a relative would keep the bloodline pure; ironically this led to the development of many genetic disorders in these families.

To understand this, we must first understand how genetic conditions are inherited. A typical person has 23 pairs of chromosomes (46 in total, if you’re good at maths😉); you inherit 23 chromosomes from your mum, and 23 chromosomes from your Dad. In each of these pairs of chromosomes, you have genes, which correspond to one another.

For example, one pair of chromosomes will hold the genes that define eye colour, so one chromosome includes the eye colour gene from the mother, let’s say it’s blue in this case, and the other chromosome includes the eye colour gene from the father, let’s say it’s brown. So why doesn’t this offspring have one blue eye and one brown eye? Well, in a lot of these traits, we have something called recessive and dominant genes. Let’s go back to eye colour. The gene which makes brown eyes is always dominant, whereas the gene for blue is always recessive, and a dominant gene will always overcome a recessive gene. A child’s eyes will only be blue if both genes on both chromosomes are the gene for blue eyes, because it is recessive and there’s no dominant gene in play. In a way, dominant genes mask recessive genes, meaning recessive genes will only have an impact if dominant genes are not there.

Now that we understand dominant and recessive genes, we can begin to understand the prevalence of genetic disorders in royal families. In many genetic disorders, the genes responsible are often recessive. Imagine if someone is a carrier for a genetic disorder but does not have the disorder itself, this means they have one faulty recessive gene, but it is being masked by a normal- functioning dominant gene. As biological relative is more likely to have a similar set of genes (one faulty recessive gene and one normal- functioning dominant gene), compared to a stranger, therefore, if this person mates with a biological relative (gross), the likelihood that the child will have TWO copies of the faulty recessive gene is increased, which means they will develop the genetic disorder. This is essentially what happened in many royal families in history.

Brother-sister and even parent-child marriages were not unusual with Egyptian Pharaohs and the Persian Dynasty. Even uncle-niece and first cousin marriages were common in early modern age royalty. As explained earlier, reproduction with biological relatives make it more likely to inherit a recessive gene which may cause a genetic disorder. An extreme example of this is the Hasburgs, who ruled from 1516-1700 in Germany. Nine out of eleven of the marriages in this dynasty were incestuous, which lead a plethora of genetic disorders. The line finally died out with Charles II, who was infertile and could barely speak or eat. The Hasburgs were characterised by the famous ‘Hasburgs Jaw’, which was a medical condition causing the lower jaw to protrude forward and was just an outward sign of their many genetic disorders.

The Hasburgs are not the only example of inbreeding in royal families; DNA studies on King Tut, an Egyptian Pharaoh, show that his parents were likely siblings, and scans of his mummified remains show that he had a cleft palate, club foot, and elongated skull; Maria I of Portugal was born into a long line of inbreeding. She was known to howl and shriek animalistic noises and have raging temper tantrums and was eventually unable to attend to her royal duties; Cousins, the Grand Duke of Hesse, and Princess Victoria, both grandchildren to Queen Victoria I, had a daughter who died when she was only eight years old and a son who was stillborn. This type of outcome was not uncommon, and the frequent inbreeding within royal families caused the children in royal families to have a higher mortality rate than the general population.

Ultimately, the fascinating history of royal families is riddled with gruesome stories of incest and genetic disorders. The attempts to keep bloodlines pure, ironically caused the spread of genetic disorders, and on occasion, wiped out entire dynasties. The marriages between cousins and even siblings meant recessive, faulty genes were more likely to be passed on which meant genetic disorders were more prevalent, and actually had the opposite effect of those they intended.

References

https://historycollection.com/16-royals-who-suffered-from-hereditary-mutations-and-defects-caused-by-inbreeding/

https://www.sciencetimes.com/articles/24610/20200107/inbreeding-among-royals-14-monarchs-who-experienced-the-side-effects-of-incest.htm

https://www.historyanswers.co.uk/kings-queens/the-dangers-of-royal-inbreeding/

https://genomesunzipped.org/inbreeding-genetic-disease-and-the-royal-wedding/

https://allthatsinteresting.com/habsburg-jaw

https://www.thesun.co.uk/tech/10464521/inbreeding-habsburg-royal-family-face-deformity/

https://www.medicalbag.com/home/features/grey-matter/impact-of-royal-inbreeding-part-iii/

Disclaimer

The information in this blog is for information and entertainment purposes only. I am not a medical professional, so I have never and will never give medical advice in this blog. You should always speak to a healthcare professional about your unique health needs. My opinions are entirely my own and do not reflect the organisations or people I work for. I only discuss published literature in this blog which are referenced with links.

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