March 1, 2024 | Rachel Seigel

Uncanny Facts About Twins

"So many good things come in pairs, like ears, socks and panda bears. But, best of all are the set of twins, with extra laughter, double grins".—Anonymous

From the bible to mythology, literature to movies and television, twins have always been the subject of great fascination. Whether it’s Mary Kate and Ashley Olsen, Fred and George Weasley or Tweedledum and Tweedledee, people can’t get enough of them, and doctors have spent years trying to figure out what makes them tick. Keep on reading for 42 mirrored facts all about twins.

1. Double Double 

Twins are two children born of the same pregnancy. Identical twins (monozygotic) come from one fertilized egg that splits in two to form two babies who have the exact same genetic makeup. Fraternal twins (dizygotic) come from two separate eggs fertilized by two different sperm and are as alike as two siblings born at different times.


2. Black & White

Believe it or not, it’s completely possible to have twins born of different races and even different fathers! It happens very rarely, but if a woman has more than one sensual partner, her ovaries can be fertilized by different sets of sperm cells on two separate occasions, resulting in multiple births. This has also been known to occur when the twins are conceived through in vitro fertilization, or even when a parent is of mixed race.


3. Doubles are Doubling

According to a report from the Center for Disease Control, the birth rate for twins has increased 76% since 1980. In 2009, one in every 30 babies born was a twin, whereas in 1980, the number was one in 53. Ok. So not quite double, but twins are definitely multiplying!


4. It Runs in the family

If you’ve ever heard stories about families with multiple sets of twins there’s a scientific reason for that; the twin gene causes women to release multiple eggs during ovulation, which increases the chances of her having fraternal twins. Since genes are passed on to family members, it’s both possible and even likely that a twin will give birth to twins.


5. You Read my Mind

A popular myth surrounding twins is that they have some kind of ESP or special telepathic ability that allows them to read each other’s minds. While no genuine scientific evidence exists to prove the claim, numerous personal accounts by twins describe a unique mental connection.


6. Unique Feature

On the surface, identical twins can be nearly impossible to tell apart, but if you really want to know which twin is which, check their belly buttons! Belly buttons are scars from cutting the umbilical chord after birth, so even identical twins will have different belly buttons. If looking under their shirts isn’t an option, you can also tell by fingerprints. A person’s fingerprints are a product of the random stresses experienced in the womb, and so far forensic experts have yet to find two sets that are exactly alike.


7. Different Birthdays

One would assume that twins are always born on the same day, but this is actually not the case. There are instances of twins being born before midnight one day and after midnight the next, and in the case of New Year’s babies, in different years. In an especially rare instance in 2011 when a couple decided to freeze their embryos and implant them a few years after their first successful in vitro fertilization, the biological "twin" of their five-year-old son was born.


8. Surprise! 

Before medical advancements such as ultrasounds were developed, a twin was often a surprise to expectant parents. Despite modern technology, twins do still manage the occasional surprise, with one twin remaining hidden from view at certain points during the pregnancy. Thankfully, the twin can’t hide for long, and after the first few months, the second baby will show up.


9. Twin Talk

The idea of twins developing their own language is a concept that has long fascinated parents and doctors. Research from the Institute of General Linguistics has found that up to 40% of twins develop their own private language that only they can understand. Just don’t expect them to teach it to you!


10. Twin Birthdays

In a “one in a million” occurrence, twin sisters in Georgia each gave birth to twin boys on the same day back in 2004. Twins definitely run in the family, so twins expecting twins wasn’t exactly a shock, but finding out you and your twin are both expecting twins on the exact same day would be pretty mind-blowing!


11. Mirror Image

Some identical twins are actually mirror images of one another. Mirror twins are born with birthmarks on opposite sides of the body from each other, opposite dominant hands, and occasionally, reversed organs. When these twins look at each other, it’s literally like seeing their reflection in a mirror.


12. Unique Individuals

People often forget that despite sharing common DNA, twins, even identical ones, are still individuals. Just like any set of siblings, it’s natural that they have similar tastes and interests, but that doesn’t mean that they act alike or even look exactly alike. In fact, as the twins get older, they might go out of their way to be different than their sibling. Dressing alike must get old really fast!


13. They’re Related? 

In real life, nobody would ever believe that Danny DeVito and Arnold Schwarzenegger could be twins (or even related), but they play twins in a 1988 movie of the same name. In the movie, they discover that they are "twins" born as a result of a genetic experiment gone wrong and were separated at birth. When they discover their connection, they set off on a wild adventure to find their birth mother.

TwinsTwins, 1988, Universal Pictures

14. Internal Interaction

Studies have shown that twins start interacting with each other in the womb as early as 14 weeks into the pregnancy. A discovery by the University of Padova found twins reaching for one another, and then touching each other a few weeks later. The twins gestured and communicated, so maybe they were already plotting!


15. Siblings or Cousins? 

When identical twins marry identical twins, it’s called a quaternary marriage. If both sets of twins have children of their own, thanks to biology, while legally being considered cousins, genetically, since they come from the same pool of chromosomes, they are technically siblings. If that doesn’t seem crazy enough, based on DNA alone, figuring out who the biological parents are of the two couples would be virtually impossible.


16. Biblical Twins

The first set of twins referenced in the bible were Jacob and Esau, fraternal twins born to Isaac (son of Abraham) and Rebekah. The book of Genesis describes them as having “struggled together within Rebekah’s womb” and when they were born, Jacob was grasping Esau’s heel. Throughout their lives, the brothers felt nothing but hostility for one another, especially since their parents played favorites with Jacob and he took away many of Esau’s rights as the first-born son.


17. Twin Constellation

According to Greek mythology, the constellation Gemini, meaning Twins in Latin, is the immortal form of twins Castor and Pollux. The twins were apparently so inseparable that when Castor, who was mortal, was ended, Pollux, who was immortal, asked Zeus to let him share in his own immortality. Zeus’s answer was to change them both into a constellation in the sky. Probably not quite what Pollux had in mind!


18. Sleep Number Mother

We already knew that mothers have super powers, but one of their particularly awesome powers is the ability of her body to automatically adjust to the temperature needs of each twin when she’s breastfeeding and carrying them. It’s like having your own private thermostat!


19. Identical but Not

Mary Kate and Ashley Olsen are possibly the wealthiest and most famous twins in the entire world. They became famous for their role as Michelle Tanner on the 80s sitcom Full House when they were just six months old, and they continued to star in a series of movies and tv shows into their teens. The girls look so much alike that they are often mistaken for identical twins, but in reality, they are fraternal twins. Could have fooled me!


20. Joined at the Hip- Literally! 

Conjoined (formerly known as Siamese) twins are identical twins who are developed from an egg that doesn’t quite manage to split all the way in the womb. These births are one in 200,000, and only 5-25% even survive. One of the earliest cases of conjoined twins was recorded in England in 1100, with two girls born joined at the hip.


21. Wonder Twin Powers, Activate! 

The Wonder Twins, Zan and Jayna, are alien siblings from the planet Exxor who first appeared in Hanna-Barbera’s animated tv series The All-New Super Friends in 1977. The twins have the unique ability to shapeshift, but with a catch—they have to touch hands in order to activate their powers. In 2013, fans of the super twins were excited by a when a poster appeared in Manhattan advertising a movie starring Mila Kunis and Ashton Kutcher, but it turned out to be a hoax.


22. Sweet Valley Twins

If you were a girl growing up in the 80s and 90s, you might remember the Sweet Valley High series, featuring identical twins Elizabeth and Jessica Wakefield. These twins epitomize the California girl: They're blonde, blue-eyed, 5'6", size 6, and have heart shaped faces. Not coincidentally, they are also Geminis. While alike in looks, they were also an example of polar opposite twins, and had extremely different personalities. The books spawned several spin-offs including Sweet Valley Kids (featuring the girls when they were seven), Sweet Valley Twins (the twins in middle school) and Sweet Valley University. The series was akin to a soap opera, and ran for twenty years, publishing 181 books. What girl didn’t wish they were a twin after reading them? I know I did!

TwinsSweet Valley High, 1994, Saban Entertainment

23. Double Records

A high school just outside of Illinois recently broke the Guinness World Record for the most multiples at one school in the same academic year. New Tier high school recorded 44 pairs of twins and one set of triplets in the class of 2020, which is three times the national average! The previous record was held by an eighth-grade class in Connecticut in 2010 with 18 pairs.


24. Terrifying Twins

One of the most terrifying movies of all time is Stanley Kubrik’s The Shining, which is based on the Stephen King novel, and one of the most iconic scenes from the film is the one featuring twins Lisa and Louise Burns as the Grady Sisters. The image of the ghostly sisters dressed in their blue dresses is enough to make even the bravest people tremble—especially when they invite young Danny to come and play… forever and ever and ever!


25. The Older You Get, the Better the Odds

Researchers in Holland have discovered that the older a woman is when she gets pregnant, the more likely she is to have twins. In layman’s terms, a hormone called FSH increases as women age, causing their ovaries to kick into high gear, causing two simultaneous ovulations. The moral of the story is that if multiple births aren’t for you, having kids early is a good way to avoid it.


26. Got Milk?

If for some reason you are anxious to have twins, according to a study in Journal of Reproductive Medicine, certain foods can improve the chances of having twins. The study compared the diets of women who ate lots of dairy products with women who followed a vegan diet, and found that the dairy eaters were five times as likely to have twins. 


27. Whodunnit

Some people say that identical twins make the perfect misconduct, and a 2009 attack case is a perfect example of why. A jewel thief managed to take $6.8 million worth of jewelry from a luxury department store in Germany, but the officers had an unexpected problem when they attempted to try the culprit for the deed. DNA scans revealed that the act was committed by an identical twin, but the courts weren’t able to figure out which of them it was and were forced to let them go!


28. Sharing a Brain

Conjoined twins Erin and Abby Delaney were born joined at the cranium, a condition which only happens one in every 2.5 million births (Talk about rare!).  The pair made headlines in fall of 2017 for undergoing a risky surgery to separate them after spending pretty much all of their ten months alive in a hospital. The surgery took 11 hours, and wasn’t without its complications, but miraculously, the twins survived, and were able to go home just before Christmas.


29. Accidental Encounter

When Tamara Rabi moved to Long Island, she couldn’t figure out why people she’d never met claimed to know her and were mixing her up with someone else. The mystery was solved when a friend of Tamara’s attended a party for a classmate from university named Adriana Scott, and realized that the resemblance between the two couldn’t be coincidental. He insisted that the girls make contact, and when they did, they learned that they were in fact identical twins who had been separated at birth. When they met, they discovered quite a few similarities, and even that they shared the same recurring dream. Freaky!


30. Switching Places

One of the "perks" of being an identical twin is the fun of occasionally switching places with one another, but just how far do they go? In the case of Ronald and Donald Anderson, they took swapping identities to a whole new level when Donald went to lock up (multiple times) in place of his brother. Unfortunately for them, their deception was discovered in 1994 when officers tried to arrest Ronald for a deed that he was already serving time for. Donald even claimed to have served in the army in Ronald’s place. Now that’s dedication!


31. Now That’s Old! 

The oldest twins ever recorded were Kin Narita and Gyn Kanie whose names literally translate to gold and silver. They lived to be 107 and 108 years old, respectively, before Kin passed from heart failure in 2000. The twins were born in 1892 in Narumi Village, Japan, and they became famous at age 99 when the mayor of Nagoya visited them on Respect for the Aged day. The twins credited their longevity with living simple lives, frequent walks, and each other’s company. As of June 2018, there were 25 sets of living twins over 100 years old, the oldest of whom will turn 106 in November.

TwinsGetty Images

32. Twins in Space

A 2018 NASA study on the impact that being in space has on a human body revealed some interesting results. The study revealed that when astronaut Scott Kelly returned to Earth after spending a year on the International Space Station, he and his identical twin Mark Kelly were no longer genetically identical. 7pc of his genes were now different than his brother’s, and it was also possible that Scott was now biologically older than his twin (and not just by minutes). When Scott found out about the change he quipped “I no longer have to call Mark my identical twin brother anymore".


33. One for the South Paws

Although left-handedness only occurs in about 10% of the population, about 17% of twins are born left-handed. Exactly why this happens is not really known, but researchers speculate that it’s related to environmental factors, hormonal levels during pregnancy, or the position of each baby in the womb.


34. Siamese Twins

The term Siamese Twins was coined with conjoined twins Eng and Chang Bunker, who were born in 1811 in (you guessed it) Siam (now Thailand), and were joined at the waist. They were sold as slaves to a circus to work as entertainers in the US and the UK where they were displayed as “the Siamese Double Boys” or “The United Brothers". Conjoined twins were something that most people had never seen before and living as long as they did defied science. When they were finally able to buy their freedom, the twins married and had 22 children between them!


35. Trickster Twins

A favorite pair of twins from literature are professional practical jokers Fred and George Weasley from the Harry Potter books and movies. The twin wizards sport the trademark Weasley ginger hair, and fittingly, were born on April 1. The actors who portrayed the pranksters in the movies are twins in real life, but while Fred is older than George, the twin playing Fred is actually the younger of the two. As to whether or not they are as mischievous as their characters? The boys confess to pulling the occasional prank on set but they left the big stuff to their fictional counterparts.


36. Passing the Gene

One common myth about twins is that they skip a generation, but this isn’t entirely true. If a woman gives birth to twins of either gender, the twin gene will be passed along to her children. Since boys don’t release eggs, they aren’t affected, but should they have daughters, the gene would be passed on again, and she would be more likely have twins. If the twins are girls however, the likelihood of the daughter giving birth to twins is pretty high.


37. Dogs Always Know

In addition to being great pets, dogs come in really handy when it comes to telling twins apart. Dogs have such a heightened sense of smell that they can tell the twins apart by their own unique smells. This also means that if either of the twins get a dog of their own when they’re older, there won’t be any confusion on the part of the dog as to which one is their owner.


38. Live Long and Prosper

While it isn’t quite the key to immortality, identical twins have been found to live longer than single birth people or even fraternal twins. The reason behind it isn’t exactly scientific, but researchers think that it has to do with the incredibly strong bond that identical twins share. Maybe that’s why so many twins live past 100!


39. Only Half Alike

In 2007, scientists discovered an entirely new and super rare type of twins known as semi-identical twins. Semi identical twins share the same genes from their mother, but different genes from their father. In other words, they are half identical and half fraternal. Researchers have two guesses about how this happened. It was either by an egg splitting first and then being fertilized by two different sperm, or it was fertilized by two different sperm first and then divided. What still isn’t known is exactly why this happened, so chalk it up to just another one of nature’s mysteries.


40. Land of Twins

The country Benin, located in Central Africa, has the highest rate of twin births in the world, with 27.9 sets born out of every 1,000 births. What causes so many twin births is still a mystery, but it might have something to do with the high consumption of a root called cassava which increases fertility and the birth of twins.

Twins Unsplash

41. Twin City

The town of Cândido Godói in South America is the twin capital of the world, with 8% of births between 1959-2008 being twins. Citizens believed that the reason for the unusually high number of twins was something in the water, but DNA tests showed that high levels of inbreeding caused an uptick in women with the "twin gene," making the births of twins more likely.


42. The Jim Twins

James "Jim" Lewis and James "Jim" Springer were born in 1940, separated practically at birth, and adopted at three weeks old to different families, never knowing the other existed. Where the story gets strange is that when the men finally met in 1979, they discovered that they’d led virtually identical lives—right down to their names and the cars they drove. Both had dogs named Toy, both enjoyed math and carpentry and hated spelling. Adding to the strangeness, both men married women named Linda, divorced, and remarried women named Betty. The uncanny similarities between the two men have led to further questions about genetics vs environment in the personalities of twins.


Sources: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37 


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