Brothers and Sisters Unite: Tales of Families Who Were a Little Too Close

Incest is one of our greatest social taboos. It’s viewed as something perverted, bizarre, and downright sickening. Our brains seem to be wired against it, and for a good reason. Inbreeding can lead to a multitude of disabilities, both physical and mental.

Albert Einstein / The Colt Clan / Mackenzie Phillips, John Phillips / Charles Darwin, Catherine Darwin.
Source: Getty Images

That being said, a handful of prominent figures throughout history have decided to ignore the dangers of incest in favor of “keeping it in the family.” Royalty often clings onto its “pure blood” for dear life, and other cultures seem to find nothing inherently wrong about it.

Here’s a list of people who have wed their cousins, uncles, aunts, and half-siblings. Some of the names will surely surprise you.

Albert Einstein

Albert Einstein developed groundbreaking theories that shaped the way we see the world today. When he wasn’t writing books, teaching, or formulating famous equations, the scientist was busy wooing the only female student in his class – Mileva Maric.

A portrait of Albert Einstein.
Photo courtesy Library of Congress/Getty Images

In 1902, their student-teacher affair went from after-class hookups to a full-on committed relationship after Mileva became pregnant with their child. Albert and Mileva married the following year. So far, no incest, right? But then came the next woman.

A Ladies’ Man

Albert’s marriage to Mileva lasted 13 years, during which he began an affair with his first cousin on his mother’s side – Elsa Löwenthal, who was also his second cousin on his dad’s side. In 1919, he divorced Mileva and married Elsa.

A portrait of Albert, Elsa, and her daughter at home.
Photo by Hulton-Deutsch/Hulton-Deutsch Collection/Corbis/Getty Images

But the story doesn’t end here. Albert also considered having a brief fling with Elsa Löwenthal’s young daughter, Ilse, who worked as his secretary at the time. Apart from his love of science, Albert was clearly fond of the ladies.

Virginia Woolf

Relationships are often complicated. But being in an incestuous one is all the more difficult. The lines between consent and deceit can be blurred. In some cases, though, the lines are clear, as they were with Virginia Woolf.

Virginia Woolf is pictured with her father.
Photo by George C Beresford/Hulton Archive/Getty Images

Both of Virginia’s half-brothers sexually abused her during her childhood and through her early adult years. First, it was Gerald who touched her when she was just six years old. Gerald wasn’t a confused 11-year-old boy. He was an 18-year-old young adult who knew exactly what he was doing.

A Tragic Ending

Later, in her adolescence, it was 29-year-old George who assaulted her. Virginia Woolf suffered immensely from sexual abuse and the complete breakdown of trust and respect for her family, people who should have cared for her and treated her with love and kindness.

Virginia Woolf poses for a portrait at home.
Photo by Gisele Freund/Photo Researchers History/Getty Images

As a result, the writer struggled psychologically all throughout her life and wrote in length about the traumatizing abuse. At 59, Virginia Woolf took her own life by drowning. Her death came after (at least) two previous suicide attempts.

The Colt Family

An Australian family was discovered in 2012, and the Colt family is one of the most extreme cases of incestual practices in the 21st century. Officials gave them the pseudonym Colt after they found the group of 40 people living in their two caravans, deprived and in poor health.

A dated picture of the Colt Clan.
Source: YouTube

Every member of the Colt family was descended from one set of grandparents, who themselves had been brother and sister. Brothers and sisters bred, fathers with their daughters, mothers with their sons, aunts with their nephews, and uncles with their nieces.

More Like a Family Web Than a Family Tree

There were even cases in the Colt family of grandparents having sex with their grandchildren. From a young age, kids in the group were encouraged – or more accurately – manipulated into having sex. The neglect was so severe that it is hard to know whether to attribute their health problems to that or to the inbreeding.

A photo of the children's bedroom.
Source: YouTube

After being discovered, 12 of the children were placed in state care, despite legal battles from the family’s adult members, nine of whom were arrested. One member, Frank Colt (age 51), was put on trial for raping his 17-year-old niece, who happened to be his half-sister too.

H.G. Wells

One of science fiction’s most memorable writers, H.G. Wells, wrote classics like War of the Worlds, The Invisible Man, and The Island of Doctor Moreau. He was also a keen advocate of the free love movement and had enjoyed his fair share of affairs in his life.

A portrait of H.G. Wells.
Source: YouTube

Wells married twice. His second wife, Amy Robbins, suffered from most of his extra-marital philandering. But it was his first marriage to a woman named Isabel Mary Wells that made headlines for being very taboo.

Love for His Cousin

H.G. Wells was married to Isabel for three years in his early twenties, between 1891 and 1894. Apart from being the light of his life, Isabel was also his cousin. At the time, Wells was working as a science teacher and wasn’t doing very well financially.

A photo of Isabel Mary Wells and H.G. Wells.
Source: Pinterest

His fame came several years later and, with it, new and exciting romantic opportunities. His first book, The Time Machine, was published in 1895, and afterward, Wells divorced his cousin and enjoyed his newfound stardom on his own.

John And Mackenzie Phillips

Mackenzie Phillips, daughter of John Phillips of the band The Mamas & The Papas, shared a 10-year incestuous relationship. It all began one night after they went on a drunken binge together. She was 19. “I woke up that night from a blackout to find myself having sex with my own father,” she told the media.

A portrait of John and Mackenzie Phillips.
Photo by Yvonne Hemsey/Getty Images

Mackenzie’s first taste of drugs was at the age of 11 when John gave his daughter a line of coke to take with him. Years later, on the night before her wedding, they embarked on a binge which led to them having sex. Or, better put, it led to John raping Mackenzie.

She Developed Stockholm Syndrome

Mackenzie called it rape, while John insisted it was “making love.” I believe the answer of what it was is pretty obvious. In any case, it developed into a decade-long incestuous relationship that ended after Mackenzie got pregnant and didn’t know whether the father was her dad or her husband.

A band portrait of The Mamas & The Papas.
Photo by Allan Tannenbaum/Getty Images

Years later, Mackenzie did an interview with Oprah Winfrey, in which she said that she developed somewhat of a “Stockholm syndrome.” The relationship was consensual, but it was also very manipulative. It was “an abuse of power … a betrayal of trust,” she explained.

John Byrne

Scottish artist John Byrne was born of an incestuous relationship between his grandfather and mother. “I presume it’s what they do in unlettered places in Ireland,” he explained, “It’s traditional, and nobody speaks about it.”

A portrait of John Byrne.
Photo by Jeff J Mitchell/WPA Pool/Getty Images

Byrne’s mother died in the ‘80s after a lifelong battle with mental illness that was probably brought on by her father’s manipulative relationship with her. So, while John didn’t seem to suffer from the incestual union, his mom did.

She Was in Love With Her Father

John’s mother was married to Patrick Byrne, who raised John and was completely clueless about his wife’s relationship with her father. “She was in love with her own father, utterly and totally,” John told the news, “She just wanted to be in his company.”

A photo of John Byrne.
Photo by Colin McPherson/Corbis/Getty Images

After hearing the news that his grandfather was actually his father, John felt instant rage. It took him years to come to terms with the man whom he had once idolized. He managed to reconcile with him because, “I admitted to myself that I adored my grandfather, beforehand… What did he do to me particularly that damaged me? I don’t think he did damage me,” John told The Times.

The Stravinskys

Despite some evidence that incestual breeding can adversely affect the offspring’s physical and mental health, that isn’t always the case. For example, Igor Stravinksy married his first cousin Katherine Nosenko who gave birth to a perfectly healthy boy named Theodore.

A portrait of Igor Stravinsky and his wife.
Source: Pinterest

Despite opposition from the Orthodox Church, Stravinsky’s wedding was allowed. While he never lived up to the incredible fame of his composer father, their son still built a successful career as a painter.

Barbara Daly and Antony Baekeland

Barbara Daly Baekeland’s story has got to be one of the most disturbing ones to date. The wealthy American socialite gave birth to a son named Antony, who was totally ignored by his posh parents, who preferred to party rather than care for him.

A photo of Barbara Baekeland / A portrait of Anthony.
Source: Pinterest

When Tony grew older, he told his parents he was gay. Having a gay son didn’t fit in with the world they had created, so Barbara tried to “cure” him by taking him to prostitutes and different women around town.

Their Relationship Took a Weird Turn

When Barbara’s husband divorced her in the mid-‘60s, she grabbed Tony and flew to London to start a new life. That’s when their mother-son relationship took a very, very weird turn. It became creepily co-dependent and complicated.

A portrait of Barbara / A photo of Tony taking a bath.
Source: YouTube

Barbara became utterly fixated on her son’s sexuality. She ended up telling her sister-in-law, “You know, I could get Tony over his sexuality if I just took him to bed.” Whether she actually slept with is debatable.

Edgar Allen Poe

Some people believe that Edgar Allen Poe never actually consummated his marriage. Others suggest that he waited for his bride to turn a certain age before marrying her. While the truth remains hidden, the story still makes us shift in our chairs.

A photo of Edgar Allen Poe / A portrait of Virginia Clemm.
Photo by ullstein bild, Getty Images / Culture Club, Getty Images

In 1929, Virginia Clemm, who was seven years old at the time, was living with her first cousin, 20-year-old Poe. In 1936, when Clemm was 13 and Poe was 27, they married (although the marriage might have been purely legal to keep them under the same roof after Clemm’s mom died).

King Rama V of Thailand

From 1868 to 1910, King Rama V oversaw Siam, now known as Thailand. The king was a very confusing person. On the one hand, he was very progressive, and on the other, very traditional and often remained loyal to age-old traditions.

A portrait of King Rama V.
Photo by Hulton Archive/Getty Images

He brought about great government reform and put a lot of money and energy into developing infrastructure. He also fought against slavery across the country. But there were a few rules this king didn’t change.

He Wed Three Half-Sisters

King Rama V made it illegal for anyone to touch the queen. The only people who could lay their hands on her were people of “royal blood.” In other words, their family. King Rama V had three queens, all of whom were also his half-sisters.

A photo of one of the Queens.
Photo by Hulton-Deutsch Collection/CORBIS/Getty Images

The King particularly liked one of the three a little bit more than the rest – Sunandha Kumariratana, whose life ended prematurely in a drowning accident. King Rama V never quite got over his half-sister/wife’s death.

Charles Darwin

Charles Darwin is probably one of the only people to have studied the effects of his own incestuous relationship in real-time. Charles Darwin married his first cousin, an act that wasn’t considered a huge deal in neither of the couple’s families.

A picture of Charles Darwin.
Photo by Hulton Archive/Getty Images

Over their 20 years together, Charles and his cousin Emma had ten children. Darwin, who had done extensive research on the debilitating consequences of inbreeding within plant species, couldn’t help but wonder what impact he and his wife’s close genes had on their kids?

“Is Marriage Between Relatives Injurious?”

Darwin kept detailed, health-related records of all the members of his family. Even though three of their kids ended up dying at a very young age, the rest of the kids who survived led extremely successful lives.

A portrait of Emma / A photo of Darwin.
Photo by Hulton Archive, Getty Images / Mrs. J.M. Cameron, Library of Congress, Corbis, VCG, Getty Images

The last paragraph of his hefty 1862 work on foreign orchids read: “Nature thus tells us, in the most emphatic manner, that she abhors perpetual self-fertilization…May we not further infer as probable… that marriage between near relatives is likewise in some way injurious?”

Moab – Lot’s First Son

Tales of incest aren’t anything new. The troubling relations have been around from the very beginning of time. According to the first book of the Bible’s Old Testament, Genesis, Lot ran off with his two virgin daughters after Sodom’s destruction.

An image of the painting The Flight of Lot and His Family from Sodom.
Photo by Fine Art Images/Heritage Images/Getty Images

The three hid away in a cave, completely separated from society. Concerned about the disappearance of their family line, they decided to do what they had to in order to save it: “Our father is old, and there is not a man in the earth to come in unto us,” the older sister told, the younger.

“Let’s Preserve the Seed of Our Father”

The story continues with the older daughter saying, “Come, let us make our father drink wine, and we will lie with him, that we may preserve the seed of our father.” She then went ahead and slept with him. When her son was born, they named him Moab.

A renaissance painting of Lot and his daughters.
Photo by Fine Art Images/Heritage Images/Getty Images

His name translates as “from my father.” Lot’s first son, Moab, grew up to become the leader of the Moabites, a tribe that would go on to fight against the people of Israel. After Moab came Ben-Ammi, Lot’s son, from his younger daughter.

Ben-Ammi – Lot’s Second Son

When Lot’s oldest daughter gave him wine and visited his bed, “he perceived not when she lay down, nor when she arose.” Which meant that Lot was completely oblivious to what was happening. His younger daughter did the same.

A painting of Lot.
Photo by Fine Art Images/Heritage Images/Getty Images

Lot’s second son was named Ben-Ammi, which translates to “son of my kin.” Ben-Ammi grew up to become the leader of the Ammonite tribe, who would also battle against the people of Israel for centuries.

Pharaoh Amenhotep I of Egypt

The ancient Egyptians have some recorded tales of incest as well. From 1526 to 1506 B.C., Pharaoh Amenhotep I, who inherited a large kingdom from his father, Ahmose I, reigned over the land and brought wealth to Egypt.

A sculpture of a Pharaoh.
Photo by Universal History Archive/Universal Images Group/Getty Images

He reopened mines and built sacred temples up in the north. He stretched the kingdom from Sudan in the south and Libya in the east. He was loved by his people. Even though his mom, Ahmose-Nefertari, was his father’s sister.

It Was Completely Normal at the Time

This wasn’t anything unusual among ancient Egypt’s royalty. Close siblings had been marrying for hundreds of years before Pharaoh Amenhotep I. He certainly wasn’t the first. And he certainly wouldn’t be the one to change things.

A photo of Egyptian pyramids on the banks of the River Nile.
Photo by Hulton Archive/Getty Images

Amenhotep I married his own sister, Ahmose-Meritamun. Marriages in the family would continue to be the norm for over a thousand years after this beloved Pharoah’s reign. This just goes to show you that as long as it’s in the norm, no one considers it to be weird.

King Tutankhamun

The impressive riches recovered from King Tutankhamun’s tomb suggest that this king of Egypt was one wealthy and powerful leader. In reality, however, that might not have been the case. Modern research has looked into this man’s life and uncovered a whole different story.

A photo of King’s Tutankhamun mask.
Photo by Fayed El-Geziry/Pacific Press/LightRocket/Getty Images

As the offspring of parents who were also brother and sister, King Tutankhamun may have suffered from a number of physical ailments, including Kohler’s disease, a cleft palate, and a club foot. His parents were siblings, after all…

His Children Were Too Weak

As history tells it, King Tutankhamun suffered from malaria, and his body grew so weak that he needed a cane to walk. Furthermore, when Tutankhamun and his younger sister wed and tried to breed, they found it too difficult to produce a healthy child.

A sculpture of the Kind and Queen.
Photo by Werner Forman/Universal Images Group/Getty Images

Desperate for a healthy heir to take over, the siblings grew more and more anxious with every failed try. Historians believe that the pair’s kids were so frail and weak that even those who survived the birth died shortly after in infancy.

Gorgo – Queen of Sparta

Tales in ancient Greek mythology are flooded with incest and other sexual taboos, but they mostly involve Gods, not humans. It wasn’t that incest was completely outlawed at the time of Sparta, but there was a consensus that if you wanted to marry your brother or sister, you should be related through your father alone.

A statue of Gorgo.
Source: Pinterest

Sharing two parents with your significant other was a bit too much for the ancient Greeks. In other words, marrying your full sibling wasn’t okay. But a half-one was fine.

Even so, when King Leonides chose his bride-to-be, he looked beyond his siblings.

He Married His Niece

King Leonides married the smartest, strongest woman he could find – his niece, Gorgo. The pair worked great together, mostly due to Gorgo’s cleverness, wit, and intelligence. They gave birth to a son, whom they named Pleistarchus.

A sketch illustration of King Leonides.
Photo by benoitb/Getty Images

Gorgo and Leonides’ son would go on to co-rule Sparta with Leotychidas II. Born as a prince, he was mentored by his uncle, Cleombrotus. Pleistarchus grew up to be a strong and reliable king who served his people well.

Queen Cleopatra

Cleopatra, the last rule of the Ptolemaic kingdom of Egypt, had a scandalous love life. Her tales are written about in history books and taught in literature classes. Her life has inspired beautiful works of art.

A portrait of Cleopatra.
Photo by Bettmann/Getty Images

The notorious queen had some questionable affairs. Cleopatra’s first wedding was to her brother, Ptolemy XIII. She was 18 at the time, and he was only ten. No one considered this to be weird. The wedding fell perfectly in line with Ptolemaic tradition.

Brotherly Love

Queen Cleopatra and her brother, Ptolemy XIII, were supposed to rule together over the land. But over the years, Cleopatra rejected her brother and husband. Her behavior angered the masses and gave way to a civil war which led to Ptolemy XIII’s demise in 47 B.C.

A sketch illustration of Cleopatra.
Photo by Hulton Archive/Getty Images

After that, Cleopatra married another one of her brothers, Ptolemy XIV. Just like the previous one, this relationship was neither romantic nor fulfilling and didn’t stop the queen from having affairs with Caesar or Antony.

Emperor Claudius and Agrippina the Younger

Unlike ancient Egypt or ancient Greek, the Roman Empire was against incest from the very beginning. The only thing acceptable in the family was marrying cousins. Anything closer than that, however, was considered “against divine law.”

A sketch illustration of Emperor Claudius / A sketch illustration of Agrippina and her son.
Photo by Bildagentur-online, Universal Images Group, Getty Images / Photo12, Universal Images Group, Getty Images

But as in most societies, the rules that apply to the common woman and man don’t necessarily apply to those who order them from high up above. Emperor Caligula, for example, slept with all three of his sisters.

A Drop of Poison

After Caligula died in 41 A.D., Claudius took his place. Claudius and his wife fought a lot, and he decided to put an end to it by putting an end to her. He executed her and went ahead and married his niece, Agrippina the Younger.

A sketch illustration of Caligula.
Photo by Historica Graphica Collection/Heritage Images/Getty Images

Agrippina, who already had a son, Nero, wanted him to be the heir. So, she manipulated Claudius into crowning him, and once she managed to convince him and the transfer of power was secured, she poisoned Claudius.

Emperor Suinin of Japan

Not much is known about Suinin, Japan’s 11th emperor who ruled from 29 B.C. to 70 A.D. There are so few records about him that his status has always been considered “legendary.” Moreover, his actions are always discussed using the prefix “allegedly.”

A sketch illustration of Emperor Suinin of Japan.
Source: Pinterest

What is known, however, is Suinin’s family tree. The interesting bit about his lineage begins with the ninth Emperor, Kaika, who reigned over the people and land for many years, had several sons, and passed away in 98 B.C.

His Best Known Legacy Is One of Incest

Emperor Kaika’s second son and Suinin’s father, Sujin, was the next one to take over the seat. Kaika’s third son, Hikoimasu, didn’t become ruler; Suinin did. Hikoimasu did, however, have a daughter, Saho-hime, who would later marry Suinin.

A painting of the Emperor.
Source: Pinterest

To make matters simple, there’s not a lot of confirmed information about the Japanese Emperor Suinin, but the one thing everyone agrees on is that he married his cousin. Basically, his best-known legacy is one of incest.

Pope Gregory I

Pope Gregory I became the head of the Catholic Church in 690 A.D. and stayed in that position for 14 years. His journey to get to that rank was arduous and filled with contrition. Abandoned as an infant, he was rescued by a fisherman who handed him to a local monastery.

A drawing of Pope Gregory I.
Photo by Hulton Archive/Getty Images

After several years, Gregory traveled to the Holy Land and undertook self-imposed penance. For 17 years, he lived in poverty and solitude. It was due to his demonstration of piety that he was chosen as the Pope.

He Took the Sin of His Parents on Himself

What the people didn’t know, however, was that the pope felt he had to undergo his penance because his parents were brother and sister. The siblings had abandoned him in shame of their taboo actions.

A sketch illustration of Pope Gregory I.
Photo by Photo 12/Universal Images Group/Getty Images

Gregory felt he was carrying the sin with him, so he distanced himself from everything and everyone to try and make peace with his parents’ decision. Their decision to sleep with each other and their decision to abandon their son.

Emperor Atahualpa of the Incas

The Incan’s last Emperor, Atahualpa, was executed by Spanish conquerors in 1533. The European invaders cited two reasons for their action: One was that he had murdered his brother to protect his position, and two, was that he had married his sister.

A sketch illustration of Atahualpa.
Photo by Heritage Art/Heritage Images/Getty Images

The Spanish had very different views on incest from the Incans. The Incans married within the family, and the practice was all very common among the Incan elite. But the Spanish Catholics were disgusted by it.

The Habsburg Dynasty

For years, royal dynasties used inbreeding as a way to keep their bloodline pure and hold the throne within the family. King Charles II, for example, from the Habsburg Dynasty, was born at the end of a long chain in which nine of 11 marriages in the family had been incestual.

A drawing of King Charles II.
Photo by Photo12/UIG/Getty Images

The impact it had on Charles was tremendous. The deformity the king had in his jaw made it hard for him to speak or chew properly. It’s said that he had a massive tongue, drooled for most of his life, and had a misshaped head.

Philip II of Spain

Another notable example of the incestuous Habsburg Dynasty was Philip II. He was a successful king who ruled over an empire which stretched all the way from the Americas to the Philippines. As a family man, however, he kept things a bit closer to home.

A drawing of Phillip II of Spain.
Photo by ZU_09/Getty Images

Philip II had four wives, each of which was a relative. His first marriage was to Manuela, his cousin, to whom he was married for three years until she passed away. His second wife, Mary I, was also his cousin. So was his third wife, Elizabeth. His fourth wife, Anna of Austria, was his niece.

Princess Maria of Portugal

The daughter of King Joseph I, princess Maria of Portugal, had a host of potential suitors at her feet. Most of them were her cousins, but Maria had eyes for someone else. At 25-years-old, she made the surprising decision to marry someone nearly twice her age.

A portrait of Princess Maria.
Photo by Fine Art Images/Heritage Images/Getty Images

But it wasn’t the age gap that threw people off. It was that he was her uncle, a 43-year-old man named Pedro. The couple led a happy life and gave birth to several children. Her eldest, Joseph, was her heir, and like mother, like son, he ended up marrying his aunt, who was twice his age (he was 15, she was 30).

James Watt

Father of the steam engine, James Watt, was a Scottish engineer who married his cousin and gave birth to six children with her. So, apart from making a dramatic contribution to human progress, Watt was also involved in some incestuous affairs.

A sketch illustration of James Watt.
Photo by Hulton Archive/Getty Images

James Watt traveled a lot across the U.K., desperately trying to make a living and sustain his wife and cousin, Margaret Miller, and their six kids. Miller died in 1773, and it would be his second wife, Anne McGregor, who got to enjoy the riches he gained because of his work.

Princess Nahienaena of Hawaii

Princess Nahienaena of Hawaii was a woman who felt trapped between old traditions and new ideas. Born to Chief Kamehameha I, who was the first ruler of the united Hawaiian Islands, Princess Nahienaena was forced to marry within the royal family.

A sketch illustration of the King and Princess Nahienaena.
Source: Getty Images

This meant that her potential suitors were her half-brothers. Nahienaena’s mom, however, had converted at one point to Christianity and was against the sin of incest. Each parent tried to pull the princess in their direction. Ultimately, she married her half-brother, and although she loved him, the marriage never felt quite natural.

King Mahidol Adulyadej

While King Rama V’s wife didn’t produce an heir (a lot of his children were either female or died early on), the King did have at least one son to pass the throne to – Mahidol Adulyadej. He was King Rama’s 86th child, and he managed to be the only male to survive long enough to claim the throne.

A young Bhumibol Adulyadej stands next to his mother, brother, and eldest sister.
Photo by Thierry Falise Collection/Thierry Falise/LightRocket/Getty Images

Mahidol’s mother, Savang Vadhana, was King Rama V’s half-sister. Despite being born to parents who were half-siblings, Mahidol wasn’t born with many issues. In 1927, he graduated with a degree in medicine from Harvard University and was regarded as Thailand’s “Father of Modern Medicine and Public Health.”

What Are the Effects of Inbreeding?

Scientists’ most common argument against incest, specifically relationships that lead to children, is that having sex within the family can massively increase the risk of being born with defects and disabilities.

An image of a mother holding her baby.
Source: Pinterest

Studies have found worrying results, with 40%-50% of kids born to first-degree relatives having some level of either physical or mental disability. Without a wide gene of pools, people are at a higher risk of being born with issues such as cleft palates, heart conditions, and facial asymmetry.

We’re Wired Against It

Our human intellect isn’t always capable of making the right choices for our future generations. We often give into temptation, lust, or our greedy need to keep the blood pure and the power within the family. Luckily, nature often comes to the rescue.

A drawing of Charles Darwin and his sister.
Photo by Hulton Archive/Getty Images

Studies have shown that there are evolutionary traits at every stage of our mating process. For one, psychologists have found that people are less attracted to someone they have seen their parents raise, even if they’re not biologically related (like an adopted sibling).

The Smelly Shirt Test

An additional finding comes from an interesting study done in 1994 called the “Smelly Shirt Test.” Woman were asked to smell the worn clothes of several men and rate how attractive they found the smell to be.

A photo of various shirts.
Photo by Aleksandr Zubkov/Getty Images

The results showed that the more different the genetics, the more the women were attracted to the smell. Another study found that sex was less satisfying among people who shared similar genetics.

What About Animal Inbreeding?

Not all organisms have developed behaviors that lower the risk of inbreeding. Bedbugs, for example, have actually used inbreeding to their advantage. Populations that have developed a resistance to insecticides have bred together to strengthen that trait in the community.

An image of a hyena.
Photo by Ayzenstayn/Getty Images

But most of the animal kingdom behaves differently. They have developed certain habits to make sure that their genes are spread more widely. For example, young male hyenas are expected to leave the herd and find a new group once they have matured.

What About Plants?

When it comes to plants, inbreeding is undesirable because it can lead to certain weaknesses. As a result, plants have developed interesting strategies to prevent it. While plants are unable to prevent pollen from entering the female sex organs, they’re still able to check its genetic viability.

A picture of a flower during harvesting season.
Photo by Patricia Galiana/Europa Press/Getty Images

If the pollen is found to be too close to home, it is chemically destroyed with a chemical known as S-RNase. Only pollen from a suitable, diverse plant is allowed to survive and thrive and keep the genetics going.