Couple welcomes rare quadruplet daughters who are actually a set of twins

Triplet birth numbers are dropping—and that may be a good thing

Pregnancies involving three kids or more have dropped 62% from 1998 to 2023, a trend that the Centers for Disease Control and Prevention links to fewer embryo transfers during assisted reproduction procedures—a transition prompted by more refined techniques and technical advances. Though multiple births can occur naturally, often pregnancies involving multiple births have been the result of efforts to ensure pregnancy success by transferring multiple embryos.

Extremely rarely, there can be twins with different dads—but fewer than 20 such cases are documented worldwide

The non-identical twins, who would also be half-siblings, result from a rare biological phenomenon called heteropaternal superfecundation. Britain's first known twins with different dads, featured in this article, learned of each other's existence in recent years, when they were both 45. They discovered each other after taking DNA tests from Ancestry, a genealogy company.

The story of the most prolific mother ever

An 18th-century Russian woman gave birth to 69 children through 27 pregnancies, with an unbelievable 16 pairs of twins, seven triplets, and four quadruplets.

Identical twin brothers marry twin sisters in double wedding—and honeymoon together

The couples exchanged vows back-to-back, allowing the brothers to serve as each other's best men, and the sisters to jump in as the maids of honor for one another. The pairs all met in a church youth group while students.Following their wedding, the couples planned to live in neighboring apartments.

Eight British children have been born via mitochondrial replacement therapy

In July 2025, a decade after British lawmakers signed off on allowing three-parent IVF, scientists announced that eight healthy babies had already been born using this approach. The news was included in a pair of research articles published in a peer-reviewed journal that noted the oldest kids were already more than two years old, and that they were hitting developmental milestones as expected. (Some users may encounter a paywall.)

Aurea is the first US baby born following polygenic analysis

The child, born in May 2020, was selected by her parents to optimize for certain health qualities based on an analysis of her multifactorial genes by a New Jersey-based company called Genomic Prediction. Her embryo was selected for implantation based on polygenic risk scores for heart disease, diabetes, and cancer.

The ultrarare 'Er' blood type has been documented only about 40 times

In 2022, the tragic loss of a pregnancy led researchers to the discovery that the rare "Er" blood type could potentially cause a mismatch in blood types between mother and fetus during pregnancy, with devastating consequences. (Some users may encounter a paywall.)

Inside the world's largest two-headed calf collection

The Two-Headed Calf MOOseum in San Francisco contains 50 taxidermied cow heads, all of which are paired with another one. They are the result of rare genetic mutations called polycephaly, that is, two-headedness. The museum is run by punk musician Henry Rosenthal, who first became captivated by the rare phenomenon in his 20s. Learn more about the exhibit here.

In 1984, a dying infant lived for three weeks with a baboon heart

Pediatric-sized hearts are very hard to find. They're about the size of a walnut. When a premature baby girl was born with a fatal heart defect in 1984 her care team transplanted a 7-month-old baboon's heart into the patient. The organ was not genetically modified but still the infant lived for several weeks. This roughly hour-long documentary from the medical institution, features the patient's mother, clinician, and more discussing the controversial procedure and aftermath.

Twin studies suggest celiac disease is among the more genetically-linked disorders

Genetics appear to play a larger part in this condition's development than many other autoimmune disorders. Research shows a roughly 60-75% genetic probability that if one identical twin has it, the other will too. Celiac triggers a small intestine attack when people eat gluten, a protein commonly found in wheat, barley, and rye.

Mark Zuckerberg has named all three of his daughters after Roman emperors

Zuckerberg studied Latin in high school and became interested in ancient Rome. He and his wife, Priscilla Chan, went to Rome on their honeymoon. His daughters—August, Maxima, and Aurelia—are all named after Roman emperors.

Danish moms have a built-in support group through the healthcare system

Local Danish health departments put these groups together, assigning mothers into small support groups comprised of mothers in roughly the same area who gave birth around the same time. The purpose of the groups is to create a supportive network of new parents who can benefit from one another's experiences. The group's mothers decide how often to meet and what to discuss.

The most common birthdays

Nine of the top 10 most common birthdays fall in September, with Sept. 9 being the most common. However, August is the most common birth month, followed by July and December. On the flip side, the least common birthdays are around major holidays, with Christmas Day being the rarest—probably due to doctors scheduling fewer inductions and C-sections on those days. Find out more birthday surprises here.

Tetrachromacy allows humans to observe 10 times the normal amount of colors

Resulting from a mutation on the X chromosome, the rare genetic condition causes individuals to possess an additional type of photoreceptor cell, typically sensitive to the orange range, located between the standard red and green cones. This enables the perception of approximately 100 million colors.

Meet the Singhs, one of India's most popular social media families

The Singh family consists of two parents and three daughters who produce tens of videos and hundreds of posts each week, all simply of their seemingly ordinary life in New Delhi, India. Ramneek, the father, began taking fun family videos while...

See photos of rare spotless giraffe born at zoo

A spotless giraffe was born at a zoo in Tennessee in the summer of 2023, with experts claiming the specimen is the only solid-colored animal of the species with genes for "reticulation," or the normal patchwork look. The phenomenon is so rare many...

Why are there as many males as females?

Pretty much every species breaks down with an equal sex-ratio, with roughly the same number of males as females. But on the surface, it appears that most species wouldn't need many males to keep the population growing, with their energy-efficient, abundant sex cell production. So why is it equal? Scientists argue an equal ratio is the most evolutionarily stable. Learn about this quirk of biology here.

Six-year-old boy in wheelchair surprises his family by walking at his graduation

The young boy was diagnosed with Noonan syndrome, a rare genetic disorder that impacts mobility and development, at just 2 months old. He usually needs a wheelchair or walker to get around, but he shocked and thrilled his parents by standing up to receive his kindergarten diploma.

The next generation of gravitational wave detectors may include a triangular design

The Einstein Telescope will use three pairs of underground detectors—each with arms separated by 60 degrees—arranged in an equilateral triangle. The European observatory will work alongside the Cosmic Explorer, a pair of new US detectors, to provide an eightfold increase in sensitivity over LIGO and extend the current detection frequency range.

The love lives of pygmy seahorses

Inch-long pygmy seahorses live fascinating lives in the Coral Triangle of Southeast Asia, where the tiny sea creatures thrive. They are one of the few species in the world where the male carries its progeny to term, in this case, after receiving an egg from the female, who keeps busy checking in on her two male mates, one of whom is always pregnant. Dive into the marine romance in this fascinating essay.

Cassatt painted more than just mothers and daughters

In one 1884 portrait, she captured her brother, Alexander Cassatt, and her nephew during a family holiday. The image is just as tender as her paintings of mothers and daughters, with the father and son—their faces near mirror images—in an intimate embrace.

Cells create more organelles and duplicate their genetic material before dividing

As part of the cell cycle, this ensures that after mitosis—the process of cell division—the two resulting daughter cells possess the tools necessary to complete the functions of their parent cell, including accumulating energy and making proteins. During meiosis, four egg or sperm cells are created, each with half the parent cell's DNA.

As of 2025, only five people have won two Nobel Prizes

Marie Curie's awards in physics and chemistry and Linus Pauling's in chemistry and peace are the only pairs in different fields. Awards to Curie's daughter and sons-in-law have made the Curies the most awarded family in history.

Doctors ignored women's pain as a nurse replaced their fentanyl with saline

This five-part podcast series, produced by Serial Productions, focuses on the experiences of women undergoing fertility treatments at a Yale clinic where a nurse secretly replaced pain medication with saline solution. This led to women experiencing excruciating pain during procedures, but the clinic downplayed or ignored their complaints.

About 2,000 US babies are born annually without some portion of their limbs, potentially leading to a lifetime of pricey prosthetics.

Ring galaxies, the rarest kind in the universe

Galaxies come in different sizes, but when it comes to shapes there are just four kinds: spiral, elliptical, irregular, and the rarest kind, ring. Ring galaxies only form in the event of a small galaxy passing through a large one, but there's more to them that that. This page explores these rare and beautiful heavenly bodies.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

See images of medical cases of firework injuries shared on this 'Instagram for doctors.' (Warning: Graphic content)

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

Salvador Dalí believed he was his own dead brother, who had died nine months before he was born

Three Ebola species are responsible for most large outbreaks of the disease, yet the only approved Ebola vaccine is known to work against just one of them.

Coral polyps reproduce via broadcast spawning, where entire reefs simultaneously release reproductive cells for about one hour, once a year.

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Up to a million Girl Scouts sell about 200 million cookie boxes every spring, generating $800 million, largely because refusing a child is frowned upon

Children are now three times more likely to say they want to be a YouTuber when they grow up than an astronaut, with some even attending 'YouTube camps' that teach kids how to create content for the platform.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

Dozens of S&P 500 stocks, including Coca-Cola and Walmart—known as the dividend aristocrats—have increased dividends every year for 25 years

Double world record holder Hunter Ewen helped conquer his fear of balloons, called globophobia, by training to win Guinness World Record titles for balloon inflation.

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

See how Budweiser's famous Clydesdales spend their days at Warm Springs Ranch, where roughly 70 to 80 of the beer brand's giant horses can be found at any given time.

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

Domino's Pizza's 30-minute delivery guarantee was responsible for the chain's 1980s surge, but it was discontinued after the company was found liable for delivery driver accidents.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

20,000 letters to the advice columnist 'Dear Abby' provide insight into prevailing sex, religion, and LGBTQ fears, anxieties, and concerns from the 1950s onward.

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

English mathematician Ada Lovelace wrote the first computer algorithm a century before computers existed and hypothesized that computing devices would one day be able to compose music—foreseeing the generative AI systems of today.

Brian Wilson wrote the Beach Boys' 'Don't Worry Baby' for the Ronettes, but the legendary girl group rejected it.

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight

The first image of a black hole was captured by creating an Earth-sized virtual observatory from a network of eight radio telescopes.