Those weird quirks siblings have in common? Darwin had a theory (2024)

Earlier this year, on New Year's Day, Emma Trenchard was on holiday in Cape Town, South Africa. She was visiting her older brother and his family, and they were out to lunch at a cafe.

"We were just waiting for our food," recalls Emma. "We'd given my niece a coloring book to keep her quiet."

Admittedly, that didn't work out too well. The 2-year-old proceeded to throw her crayons under the table.

"There wasn't room really to go down with your arms cause the table was very tight to the seating bench," Emma says. So instead, she slipped off her shoes and started picking up the crayons — with her feet.

"I mean, if you've got bare feet," she explains, "it makes more sense to pick it up with your foot than it does to crawl under the table and pick it out with your hands."

Those weird quirks siblings have in common? Darwin had a theory (1)

/ Aurélie Marrier d'Unienville


Aurélie Marrier d'Unienville

Emma has always had unusually dexterous feet. For years, she's used them as a second pair of hands, often for picking up things like rolling papers or cigarette filters. As an artist, she's also used them to sketch portraits.

"I broke my thumb and I just drew with my feet all the time," she says. "It's a good way to loosen up if you use your toes instead."

At the cafe in Cape Town, Emma was grabbing the crayons with her feet when she noticed that her older brother, Tommy, was doing the same thing.

"So then it got quite competitive really," she says. "It became a sort of toe battle. Until we realized we both had our bare, knobbly feet out, putting things on the table and everyone was trying to eat their lunch."

"Judging from people's reactions, this was not normal behavior," says Tommy. "Had a few looks from people who seemed to think we were doing something very odd."

Those weird quirks siblings have in common? Darwin had a theory (2)

/ Aurélie Marrier d'Unienville


Aurélie Marrier d'Unienville

Tommy is also especially versatile with his feet. He routinely grabs coins, car keys, rubber bands, remote controls and even tennis balls.

"I suppose I haven't really found many things I can't pick up with my toes," he says. "I spend a lot of time with my daughter in my arms and there's usually stuff all over the floor. Instead of having to bend down all the time, it just seems so much easier to pick everything up with my toes."

Even among siblings, though, it's survival of the fittest. Emma is quick to point out that at that cafe in Cape Town, she bested her brother in picking up the crayons. "I definitely did win the battle," she says.

So can you throw an object using your head?

It's not a surprise when siblings are alike. There are numerous sibling piano prodigies, chess whizzes and star athletes. But sometimes, there's a trait that siblings share that's so unusual — like the dexterous feet of the Trenchards — that it cries out for a deeper look.

Nancy L. Segal, a psychologist at California State University, Fullerton, says she's impressed with the Trenchards' unique ability. "I find that rather extraordinary," she says, "because I don't think that picking up things with your feet with that kind of dexterity is that common."

It's possible that genetics is partly responsible, even if neither of their parents can do this fancy footwork. "Just by chance, siblings can inherit the same combinations of genes from their parents to give rise to these unusual kinds of behaviors," Segal suggests. "Or it could be that this trait was in their family generation years ago and for some reason was unexpressed."

This reasoning goes back to at least Charles Darwin. In his 1871 book The Descent of Man, he described a set of male family members who could all contract muscles in their scalps to throw objects using their heads. "This case offers a good illustration," Darwin wrote, "how persistently an absolutely useless faculty may be transmitted."

Segal says there's one category of siblings that share oodles of these "useless faculties" — identical twins.

"You see these similarities more often with identical twins raised apart than with fraternal twins raised together," she explains. Segal reasons it has to do with our genes. "The more unusual or atypical the similarity, the more you believe that it's got some sort of a genetic underpinning or at least a partial genetic underpinning."

Segal has examined these shared quirks and their origins in the Minnesota Study of Twins Reared Apart and more recently with twins born in China who were separated due to the one-child policy.

She says in both studies, when these twins reunite, they discover an ocean of shared oddities.

"We had twins who read books from back to front," she says, "and twins who liked rubber bands around their wrists, and twins who hated a vase in the middle of a restaurant table because it blocked the view of the other person. So they'd shove it aside. A pair of Scottish ladies would eat toast, they'd cut it into four pieces and always leave the last one. That's just how they did things."

And this is just scratching the surface. Dig a little deeper with a particular pair of twins, and all sorts of curious similarities emerge.

Separated twins: same lipstick, same tea habit

Sharon Poset and Debbie Mehlman just turned 72. They're identical twins who were separated at birth when they were adopted by different families.

Growing up, Poset says she always felt like something was missing. "I was always lonely," she says. "Always."

Those weird quirks siblings have in common? Darwin had a theory (3)

/ Charity Rachelle for NPR; Jodi Hilton for NPR


Charity Rachelle for NPR; Jodi Hilton for NPR

For years, Mehlman felt the same way. She wanted someone her age to go on vacation with and have sleepovers with. "I always wished there was somebody out there," she says.

Then, when she was 45, Mehlman found out from her adopted mother that there had been two babies. She hired a private investigator. Before she knew it, she was speaking with her twin sister on the phone. The two agreed to meet, so Poset flew from Kentucky, where she lived at the time, to Connecticut, Mehlman's home state. Her twin was waiting for her at the airport.

"And it was just the most amazing connection," recalls Poset, who now lives in Alabama.

On the one hand, they were strangers. But they were clearly cut from the same cloth. "We had the same lipstick on," says Poset. "We always run late. We set our watches like nine minutes ahead of time" so they won't ever be late. "We listen to classical music. We drink tea about five times a day — hot tea."

Mehlman says that after using a paper towel, she'll lay it out to dry to reuse it. "I'm not throwing this out after one time," she says. She couldn't believe when she saw Poset doing the same thing. "I go, 'You do that too?' And she goes, 'Yeah, I don't like to waste them.'"

They also express exasperation identically — first they cross their eyes, and then they roll them. "We've both done that since we were little," says Mehlman. "If something is really stupid, you're like, 'Oh my god, I can't believe it.'"

Those weird quirks siblings have in common? Darwin had a theory (4)

/ Charity Rachelle for NPR; Jodi Hilton for NPR


Charity Rachelle for NPR; Jodi Hilton for NPR

There are deeper currents of similarity, too. They were both professional social workers — which stemmed from a shared interest in caring for others. They're both religious — Poset's Christian, Mehlman's Jewish — and involved with their respective faith communities.

The two do differ, naturally. Poset loves to garden. Mehlman won't do anything that dirties her fingers. Poset won't step foot in a gym. Mehlman exercises regularly. "So it's not like we're clones of each other," admits Mehlman.

But both say they find a profound comfort in the things they do share. The overlap doesn't make them feel any less unique. "I see how you could feel that way," says Poset, "but it's more of a compliment that somebody else does it too that you admire and love."

Poset and Mehlman are like dozens of pairs of identical twins studied by Segal over the years. Her research, she says, leads to a clear message: "Many of our behaviors that we think we just acquired by random chance are not a matter of random chance."

Segal doesn't discount the influence of the environment. But she concludes our genes may determine the foundation of what makes each of us an individual, quirks and all — qualities some of us share with our siblings.

These siblings go toe-to-toe

As for Emma Trenchard, who picks up crayons with her toes, she's always felt close to her older brother Tommy. In addition to the foot thing, she says they both have a love of travel and of activities that lead to an adrenaline rush.

"It's nice to know that you share so much." she says. "I wouldn't have wanted another sibling. Apparently, my mother asked me if I wanted another one? And I said, 'No, I don't want to share Tommy with anyone.'"

They don't see each other that often these days — he lives in South Africa and she's in England. She says she misses him, which is why those visits to Cape Town are so special to her.

"A relationship with a sibling is just unlike any other relationship," says Emma. "Your sibling is so close to you... is part of you, really." For her, that closeness is magnified whenever she and Tommy are able to achieve the same feet ... er ... feat.

Your turn: Tell us about an unusual trait you share with a sibling

Do you and a sibling have an unusual trait in common – picking up keys with your toes, preparing your toast in a special way, setting your watch 9 minutes ahead so you'll never run late? We'd love to hear about it – how you first discovered this quirk-in-common and whether it makes you and your sibling feel especially close. Email us at with the subject line "Sibling similarities." We may feature your story on Please include your name and location. Submissions close on Monday, May 13.

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Those weird quirks siblings have in common? Darwin had a theory (2024)
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