The Most Inbred Habsburg Ever Born – And His Body Paid The Price

For 200 years, one family tried to keep their bloodline pure. They married their own nieces, cousins, and aunt’s children over and over. Then, in 1661, their masterpiece arrived. A fragile little boy who couldn’t stand up straight. What his autopsy revealed 38 years later would end a whole dynasty and start a war that killed a million people.

His name was Carlos II and he was born in Madrid on the 6th of November, 1661. His father was Philip IV, king of Spain, and one of the biggest kingdoms in Europe. His mother was a Habsburg from Vienna named Mariana. She was also his father’s real blood niece, the daughter of Philip’s own sister. Philip was 30 years older than her when they married, but this kind of thing wasn’t unusual in the family.

It was actually the plan. They’d been doing it for over a hundred years by then, marrying inside their own bloodline to keep the crown from slipping to anyone else. The plan was starting to break with Carlos. His older brother, Philip Prospero, the previous heir, had died of a seizure just 5 days before Carlos was born.

Out of five children Philip and Mariana had together, only two would make it past childhood. Carlos was one of them. The other was his sister, Margaret Teresa, the little blonde girl in that famous painting where she stares out at you in a giant silver dress. Margaret got the lucky ticket. Carlos drew the shortest straw of any royal born in Europe.

Something was already wrong at his birth. A quick birth notice went out saying Carlos was robust, handsome, and well-proportioned with fine black hair. That was the official line. The private letters told a different story. Ambassadors writing back to the Vienna and Paris described a baby covered in scabs with a rash on both cheeks and a strange leaking sore below his right ear.

He couldn’t hold his head up on his own for months longer than a normal baby. His legs wouldn’t hold him at age three. When he finally did walk at nearly seven, he wobbled like a much older man. He wore leg braces until his fifth birthday because his bones were too weak to carry him. 14 wet nurses rotated through the palace nursery because he couldn’t suckle properly.

He didn’t speak a real word until he was four. Plenty of kids develop late, sure. But Carlos wasn’t just delayed. His whole body seemed to be building itself wrong from the inside out and nobody in Madrid could figure out why. That famous Habsburg jaw hit him harder than any relative before him. That jaw, the one you’ve probably seen in a museum painting, ran in the family for centuries.

It’s officially called mandibular prognathism. The lower jaw juts out so far past the upper one that the teeth can’t meet. Some Habsburgs had it mildly and could live with it fine. Charles V had a milder version. Philip IV had a much worse one. But in Carlos, this thing went to a whole other level. His lower jaw stuck out so far that his mouth wouldn’t close.

He couldn’t chew his food. Anything solid had to be mashed or he’d swallow chunks whole and throw them back up. Another problem sat on top of the jaw. His tongue was too big for his mouth, a condition doctors today call macroglossia. It meant he He constantly into his silk collars, and his speech came out muffled.

Foreign ambassadors wrote embarrassed reports back home. They said they hadn’t caught a single word out of the King of Spain. In 2019, a Spanish team studied 66 royal portraits and confirmed what everyone had suspected for centuries. The jaw wasn’t a coincidence. It was linked directly to how closely each king’s parents were related.

And Carlos was the worst case they measured. Doctors back then were completely lost. Nobody in Europe had the science to explain what was happening to Carlos. Germs hadn’t been discovered. DNA was hundreds of years from being understood. So, the physicians of Madrid did what physicians of Madrid always did. They bled him repeatedly.

Doctors put freshly killed pigeons on his head, warm and still dripping, because they believed the birds could pull sickness out through the skull. Steaming animal guts got wrapped around his stomach. Powdered emeralds were mixed with his wine. When he had seizures, they made him drink broths of horn shavings and human bone dust.

None of it worked, because none of it could. His family knew he was fragile, though. They knew he was different from the other royal children. So, they let him grow up almost never leaving the palace, almost never seeing sunlight, almost never touched by anyone outside his mother and his nurses. He was raised like a rare piece of glass, and that made him weaker, not stronger.

Sickness came easily to him. He caught measles, chickenpox, and smallpox before he was 10, and somehow survived all three. Every survival made the succession look a little more fragile. And the whole court a little more nervous about what would come next. Meanwhile, his mother, Mariana, was quietly running Spain in his name.

Mariana of Austria became regent the moment Philip the fourth died in 1665. Carlos was 3 years old at the time. He couldn’t rule, and he probably wouldn’t understand what ruling meant for another decade. So, Mariana took the throne behind the throne. She was smart. She was Austrian, and she was surrounded by enemies at court.

Her first favorite was her own confessor, an Austrian Jesuit named Juan Everardo Nithard. Nobody in Madrid liked him because he wasn’t Spanish. Her second favorite was a courtier named Fernando de Valenzuela, hated for coming from nothing. Behind all of that stood Don Juan José, Philip the fourth’s illegitimate son with an actress.

He was popular, handsome, a decorated general, and he wanted power. He led a coup against his stepmother in 1677, exiled Valenzuela, and took over the government. When he died 2 years later, Mariana came right back. Through all of this, Carlos sat in the middle, pulled between his mother and his half-brother, signing whatever papers his ministers pushed at him.

The empire kept losing wars and losing money, but nobody was really telling the king. He was too fragile to hear about it. Spain kept sliding through the ’80s, losing battles in Flanders and money to bad harvests. Meanwhile, Carlos kept coughing his way through his 20s. And something even stranger was starting to happen at court.

By his 30s, the whole court had decided Carlos was bewitched. That isn’t an exaggeration. It’s why history books still call him Carlos the Bewitched, or in Spanish, Carlos El Hechizado. In January 1698, Carlos himself asked the Grand Inquisitor to look into whether he was under a demonic spell. His personal confessor, a monk named Froilán Díaz, took the assignment dead seriously.

Froilán knew of a convent up in the mountains of Asturias where several nuns were supposedly possessed. He arranged for an exorcist to interrogate the demons speaking through those nuns. And the demons, through the possessed sisters, gave an answer. The king had been cursed twice, they said. Once as a boy of 10 to make him sick, then a second time in adulthood to make him infertile.

The weapon had been a cup of chocolate laced with the brain and kidneys and intestines of an executed criminal. According to the possessed nuns, the person behind the curse was Carlos’s own mother. She’d done it to keep him weak so she could hold onto her power. The Bishop of Oviedo, hearing all of this, wrote back with the only sane response of the whole affair.

He said the king wasn’t cursed at all, just sick and dominated by his wife. What he needed was medicine, not exorcists. But nobody in Madrid wanted to hear that. Which is how a French teenager named Marie Louise ended up in Madrid. Spain desperately needed an heir. If Carlos died childless, the empire would collapse into a European free-for-all.

So they picked him a French bride. Her name was Marie Louise of Orléans. She was 17 years old, and her uncle happened to be Louis the 14th. She’d grown up at the glittering court Versailles. She thought she was going to marry a French prince. Instead, she was shipped off to Madrid to marry a man who couldn’t chew his own food.

She cried the entire journey there. When she arrived in Spain in 1679, Carlos was 18 and he genuinely fell for her. He wrote her love letters. He gave her jewels of every kind. Whole rooms of the palace were rebuilt for her comfort. Marie Louise, despite her horror at her situation, grew fond of him, too. But nine years passed and no baby ever came.

She wrote miserable letters back to her family about her loneliness, her strange husband, and the dowager queen who watched her every move. Then, in February 1689, at just 26, Marie Louise suddenly died. Her last words to Carlos, according to court witnesses, were, “Many women may be with your majesty, but none will love him more than I do.

” Rumors instantly started that she’d been poisoned. Historians today think she died of a burst appendix. Either way, the succession problem was now worse than ever. After Marie Louise died young, they tried again with Maria Anna of Neuburg. This time they picked strategically. Maria Anna of Neuburg was German, from a Bavarian family famous for one specific thing, extreme fertility.

Her mother had produced 17 children. Her sisters were popping out heirs everywhere they went. The Spanish court decided that if any woman on earth could get Carlos to father a son, it was her. She arrived in Madrid in 1690. Within months, it was clear something was very wrong. Maria Anna herself was ambitious and pushy, and she made enemies at court fast.

But the actual problem wasn’t her. The queen reportedly confessed to close friends that the king simply couldn’t perform in bed. Actually paid a laundry woman to steal the royal bed linens so he could examine them for evidence. Whatever he found or didn’t find, no child ever came. For a decade, Maria Anna lived in a palace full of spies, watching her husband physically fall apart.

He started losing his hair in his early 30s. He looked like an old man before he was 40. His seizures got worse every year that passed. And the real mystery of what was actually wrong with him would only be uncovered by scientists more than 300 years after his death. None of it was witchcraft, though. The real answer sat in his family tree.

Every human being has 32 great great great grandparents. Two parents, four grandparents, eight great grandparents, and so on. It doubles every generation. Except when it doesn’t. When cousins marry cousins over and over, that number stops doubling. The same names start showing up in more than one slot. This is called pedigree collapse.

And Carlos was possibly the worst case in recorded royal history. Instead of 32 unique great great great grandparents, he had far fewer. The same handful of Habsburgs kept appearing again and again in his ancestry. All eight of his great grandparents descended from one single woman, Juana of Castile, called Juana la Loca, or Joanna the Mad.

She shows up as two of his 16 great great, great grandmothers. She appears again as six of his 32 great, great, great, great grandmothers. And she surfaces six more times among his 64 great, great, great, great, great grandmothers. His own mother, Mariana, wasn’t just his mother. She was also his first cousin’s daughter.

His grandmother, Margaret of Austria, was also his great aunt. Every branch of the family tree looped back through the same few dead relatives. When scientists finally plotted it all out in the 21st century, the number they got made them stop and check their math. Three scientists in Santiago de Compostela finally proved it in 2009.

Their names were Gonzalo Alvarez, Francisco Ceballos, and Celsa Quintero. They built a genealogical database of more than 3,000 people going back 16 generations across the Habsburg dynasty. Their paper was published in the journal PLoS One in April 2009. The number they calculated for Carlos was 0.254. What does that mean in plain terms? It means his inbreeding coefficient, the estimated share of his DNA where both copies of a gene came from the same ancestor, was as high as it would be if his parents had been full brother and

sister, or father and daughter. And it was actually a touch higher than either of those because centuries of Habsburg intermarriage had stacked on top of his parents’ uncle-niece union. In simple language, Carlos’s genome was collapsing. Roughly a quarter of it was carrying identical bad copies of the same recessive genes.

Any hidden defect his ancestors had quietly carried, he was almost guaranteed to express. Combined pituitary deficiency, kidney malformations, seizure disorders, infertility, the whole grim shopping list. The same study found that across the entire dynasty, the more inbred a child was, the less likely they were to survive to age 10.

First cousin marriages alone dropped survival by nearly 18%. At Carlos’s level of inbreeding, that survival rate crashed below half. Carlos’s last few years were brutal to watch. By his mid-30s, Carlos already looked 70. His hair had fallen out and his teeth were rotting. His feet, legs, belly, face, and even his tongue swelled with fluid.

Whole days went by when he couldn’t leave his bed. The French ambassador, Harcourt, wrote to Louis XIV in March 1698. He said the king was so weak he couldn’t sit up in his chair for more than an hour. His body was giving out from every angle, with constant diarrhea, blood in his urine, and food that just wouldn’t stay down.

The exorcists were still coming and going. Fresh pigeons were still being applied to his skull. Warm animal guts were still being wrapped around his belly. Priests were rotated day and night to say masses over him. Meanwhile, every court in Europe was quietly waiting for him to die because they’d all drawn up plans for what would happen when he did.

Louis XIV of France wanted his own grandson on the Spanish throne. Emperor Leopold of Austria wanted his own son on it. The English and the Dutch didn’t want either of them because either choice would upset the balance of power on the continent. Carlos, the dying man in the middle of it all, knew exactly what was coming.

He just couldn’t stop it. He died on the 1st of November, 1700, 5 days before his 39th birthday. Because so many people still believed he’d been bewitched, they did something unusual for a king. They performed an autopsy on his body. What the physicians wrote down that day has been repeated in history books ever since.

Some of it was almost certainly exaggerated for drama. The famous version claims his body held not a single drop of blood. His heart was the size of a peppercorn. Both lungs were corroded. His intestines were rotten and gangrenous. His single testicle was black as coal. And his skull was full of water. Some of that was probably period drama, especially the peppercorn heart and the missing blood.

But the credible parts of the report are grim enough on their own. He had one atrophied testicle. His kidneys held large stones. His skull contained abnormal fluid, which lines up with modern theories that he suffered from hydrocephalus. And multiple organs showed signs of long-term disease. In 2009, the same researchers who calculated his inbreeding also proposed that Carlos had carried two rare recessive disorders at once.

One hitting his pituitary gland, and one his kidneys. In 2021, another team suggested a single storage disease called aspartylglucosaminuria could explain almost everything about him. Whatever the exact diagnosis, his body had simply run out of working parts. The moment he died, Europe went to war over his throne.

In his final will, signed just weeks before he died, Carlos named Philip of Anjou, the 16-year-old grandson of Louis the 14th of France as his sole heir. That one signature was the biggest political earthquake of the century. Austria refused to accept it. England and the Dutch Republic said no as well. Within 9 months of Carlos’s funeral, most of Europe was at war.

It’s called the War of the Spanish Succession. The fighting lasted 13 years from 1701 to 17 14. Battles raged across Europe, the Caribbean, and even North America. Historians estimate the combined casualties in the hundreds of thousands with some serious estimates running past a million once you count disease and starvation.

In the end, Philip kept the Spanish crown, but only after promising to renounce any claim to the French one. Spain lost the Netherlands, most of its Italian territories, Gibraltar, and Minorca. Britain came out of it a global superpower. The Habsburg dynasty in Spain, the one that had spent 200 years marrying its own relatives to keep the crown in the family, was over.

All that effort, generation after generation of aunts marrying nephews and cousins marrying cousins, ended with one drooling, dying man who couldn’t produce a single heir. His body had paid the price, but so had an entire continent. That’s the strange, sad story of Carlos II, the most inbred royal in European history.