Inbreeding is reproducing with someone who is closely related in terms of genetics. Such a parent, sibling, uncle/aunt or even a cousin.
This has been a known practice when it comes to breeding cats and dogs and a lot of people are critical of inbreeding animals as it can be seen as immoral and animal cruelty. Due to the amount of inbreeding within dogs and cats, a lot of them born sick and die sick.
If both parents were genetically related and one or both parents carried a faulty gene the puppy would also get that fault. When the parents are not genetically related, the puppy has more choice of genes and can override the faulty gene. So it is recommended when breeding animals that out-breeding is the best choice of having healthy offspring.
With that in mind, how does inbreeding bode for humans?
Let's start with an brief basic of human genetics
So we know if you have a child with someone genetically close to you like a sibling or a cousin, it might mean that the child inherits two recessive genes. Sibling to sibling inbreeding is told to be far much riskier than reproducing with a cousin or aunt/uncle... and for some strange people, grandparents.
Scientists say that inbreeding is not a good idea as it might be harmful to that child as they can develop genetic disorders, have a short stature, a weak immune system, have a asymmetrical face and problems with their heart. In some cases, the child may die soon after birth.
Now let's look at some people that took the risk of inbreeding and what happened to their children.
I chose to cover history of royal families around the world as it was believed at the time to be a nobility as they mistakenly thought reproducing with their own family would develop super-children and maintain a pure blood line.
People who were in the royal family didn't exactly have a massive pool of people they could choose to procreate with, but it was law to stick breeding within the family.
King Tutankhamun of Egypt
(Reigned 1332 - 1323 BC)
King Tut was an Egyptian Pharaoh that reigned over Egypt for 9 years, until he died age 18 from what is thought to have been complications of genetic disorders.
King Tut's parents were both siblings, as tests of mitochondrial DNA proved this to be fact.
Scientists tell us as a result of inbreeding, King Tut went through hell and that his life was perpetual suffering. He spent most of his life sitting as he suffered from Kohler's disease. It's a rare disease that starts within childhood and the bones in the feet die and collapses on itself. It's known to be extremely painful.
He also had a large overbite and feminine thighs, add to that a cleft palate and a bent spine. It is also said he couldn't move his head well because seven of the vertebrae in his neck was fused together.
King George III of United Kingdom
(Reigned 1760 - 1820)
King George III was an English king but more well-known as "Mad King George" and it's thought his madness might have been the result of inbreeding.
It was thought that George wouldn't survive the first few days after his birth as he came out 2 months prematurely but nonetheless he surprised everyone with his recovery and grew up in the House of Hanover.
House of Hanover was notorious for cousin to cousin marriage, some first cousins and other times second or third. It was happening all over Europe in the 18th Century and is said that every heredity monarch in Europe was clinically insane.
It was said that King George III suffered a genetic blood disorder called porphyria, which would make him ache a lot and reported that his urine was blue.
Many witnesses including monarches, family members and people working in the castle had reported King George III just couldn't stop talking and other times have convulsions.
When he got older he was almost blind with cataracts and had terrible rheumatism.
In 1801, George was taken to the hospital in a straight-jacket and he was not seen again in public. 19 years later, he died clinically insane and didn't know who he was.
King Charles II of Spain
(Reigned 1665 - 1700)
King Charles II of Spain was from the Habsburg family, a house with a very shallow gene pool.
I should mention that inbreeding between European nobility was very common in the early ages but not all children inherited genetic disorders/complications.
But this wasn't the case for King Charles II as his parents were genetically niece and uncle. This had a nasty effect on his appearance and was given the name "The Bewitched".
He was short, physically disabled, epileptic, senile and completely bald before the age of 35 and was always on the verge of death.
He did not learn to talk until he was 4 years old and he did not learn to walk until he was 8. He could barely speak because he had something known as the "Habsburg Lip". This meant the lower jaw stretched out way further then the upper jaw, making him look deformed.
He also had a very large tongue, which didn't help with speaking either.
It is blamed on royal intermarriage and historians tells us the Habsburgs were the inbreeding champions of Europe.
King Charles II died at just age 39, where he was born sick and died sick as quoted by an unknown writer "We are dealing with a man who died of poison 200 years before he was born"... referring to 2 centuries of inbreeding.
The physician that did King Charles II autopsy after his death reported that Charles did not contain a single drop of blood in his body, his heart was 10x smaller than average, his lungs corroded; his intestines rotten and gangrenous, only had one testicle that was black as coal and his head was full of water.
This information and research suggests that inbreeding depression for infant and child survival could be occurring in the Spanish Habsberg families as a consequence of prolonged incestuous marriages.
King Chulalongkorn of Thailand
(Reigned 1868 - 1910)
King Chulalongkorn was the great king of Thailand in the late 1800's and was responsible for modernising the country and very well liked. He abolished slavery, reformed the government, built modern hospitals and introduced a new law system.
He also had 4 wives, all of which were his half-sisters. He was a busy man as he also had 32 consorts and 116 concubines. In total, he had 33 sons and 44 daughters.
Many of his children lived long lives, but many others were sickly and lived very short lives.
As he had so many children, it's hard to cover them all but it's thought the children he had with his half-sisters died from a result of inbreeding.
Princess Nahienaena of Hawaii
(Born 1815 - 1836)
Princess Nahienaena's life was short lived as she died at the age of 21.
In the 19th Century, it's said in Hawaii that incest was a privilege and this princess married her brother, Prince Kauikeaouli. They had a child but sadly died shortly after birth, many believe the cause of death due to generations of inbreeding.
Princess Nahienaena never recovered from the loss of her child and died 3 months later.
Tsarevich Alexei Nikolaevich of Russia
(Born 1904 - 1918)
Alexei Nikolaevich was the heir to the throne of the Russian Empire, but sadly his life was not a long one and died at age 13.
He was the youngest of 5 children and suffered from hemophilia, a condition where the blood does not clot and would bleed out longer after sustaining injury and prone to higher risks of infection.
Recent studies have shown the reason Alexei suffered from hemophilia is that he is a descendent of Queen Victoria I of United Kingdom, who also had this disease.
In fact, a lot of Queen Victoria I's genetic relatives had suffered from hemophilia, it was even called the "Royal Disease" and the mutation for hemophilia was spread through to various royal houses. As stated at beginning, it wouldn't go down well as recessive genes with recessive genes means passing down faulty genes.
Queen Victoria's son, Prince Leopold, died at age 31 of a brain hemorrhage.
Her grandson, Prince Friedrich of Hesse and by Rhine, met the same fate.
Her great grandson, Prince Waldemar of Prussia bled to death... the list of Queen Victoria's descendents whose death was related to hemophilia is endless.
Queen Maria I of Portugal
(Reigned 1777 - 1816)
Another mad royal, Queen Maria I was said to go into fits of hysteria.
During her rule, 2 of her children died of smallpox which didn't help her mental health condition.
It was reported by her handmaidens that Queen Maria would stay alone in her room howling and crying and it's said that many people in her family suffered from mental diseases.
The blame is said that it's the inbreeding responsible as both of Queen Maria's grandfather's suffered mental problems too. Maria ended up marrying her uncle and one of her son's married his aunt.
Elisabeth of Austria
(Born 1837 - 1866)
Elisabeth is a member of the family-loving Habsburg household. Elisabeth was married at just 16 years old to her cousin, Franz Joseph I of Austria. But as you would know, for the Habsburgs, this was the norm.
The Habsburg family tree looks more like an actual family branch.
Elisabeth came from the very inbred House of Wittelsbach. She suffered from depression most of her life and became obsessive about her looks to the point of starving herself. She was eventually murdered but her mental illness is believed, once again, to be a result of inbreeding.