What's better than keeping up with your favorite actor? 

Maybe it's finding out that there's more DNA where they came from!

Famous siblings are relatively common, of course, from the Brothers Hemsworth and Jonas to the trio of sisters who make up the band Haim, and so many stars count one or more siblings as their best friends in the world, business partners, roommates, etc. But there are only so many who bunked together before they were even born. 

There are sets of celebrity twins you know well because they've been building their brand together every step of the way, à la Mary-Kate and Ashley Olsen, and others who you've seen a lot of, only...you're just not sure which one is in which thing.

And then there are stars who were born as one-half of a pair and their brother or sister has a regular job, so you may not know who they are—but rest assured that their biggest fan is usually their twin. Or, in Gisele Bündchen's case, her business manager!

"If there is a truly altruistic person I know in my life, it's my brother," Scarlett Johansson told People in 2020 of her twin, Hunter, who founded the first-responder aid organization Solar Responders. "He reminds me to be a better person all the time. I'm incredibly proud of him."

In honor of National Twins day August 6—we're looking at you Ashton Kutcher and brother Michael—here are the celebs with twins you didn't know about, or a sibling you didn't know was their twin:

At birth, Ashton weighed 10.5 pounds and Michael, a surprise arrival five minutes later to parents who thought they were expecting a son, weighed 4 pounds. "I tell people he must have ate everything while we were in the womb," Michael, who was diagnosed with cerebral palsy at 3 and received a heart transplant at 13, told the Associated Press in 2012.

But the activist and father of three eventually forgave Ashton—for his big appetite and for spilling the beans about Michael's condition years ago in an interview.

"I was very angry. Very angry. I remember speaking to him about it," Michael told TODAY Parents in May. "I didn't want to be the face of CP. I never talked about it." Ultimately, however, he realized that "Chris [Ashton's actual first name] did me the biggest favor he's ever done because he allowed me to be myself."

The That '70s Show star told TODAY Parents, "My brother's daily actions remind me that life isn't about running around challenges—it's about running through them. Mike has a relentless work ethic and a deep compassion for others."

"There are few places and moments when my sister can move about without being recognized," Hunter told Parade in 2015, noting that they led "very normal city lives" growing up with their two older siblings in New York. "When those rare instances happen," he continued, "I am reminded of a time before her celebrity, when we were kids, and I treasure that. She is my other half. Nothing is more important to me than my twin."

Scarlett would agree, saying of her activist brother, who at the time was working at a nonprofit that was helping to rebuild homes after Hurricane Sandy, "I feel very connected to him. He's the most golden-hearted person. I think a lot of people spend their life looking for a partner, someone to be a mirror to reflect upon, to remind them that they've lived. You want someone to tell you what he witnessed in your life. My twin brother has always been that for me."

Yes, they've pretended to be each other here and there over the years. Sami, who's younger by four minutes, is a teacher now, but as kids "we did some bad stuff," Rami said on Jimmy Kimmel Live, noting that they've looked less exactly the same as time has gone by.

Luckily their version of bad-boy behavior was Rami performing a monologue from a Greek tragedy for his unprepared brother in class one day. "It's going to give me the points I need to get my degree," the actor recalled Sami, who was a few units shy of graduating, telling him. In Rami's version of events, after the applause he garnered raised the teacher's suspicions, she pulled him aside and asked, "'How did you learn how to do that?'" He replied, "'Oh, it's just a hobby.'" She asked if he would perform an encore for her next class, but he excused himself, saying he was parked in a red zone and had to go.

It's been fairly easy for Paul to drive under the radar since his fraternal twin, Mark Sinclair, opted for a memorable stage name.

Talking about a photo of his real brother standing with Paul Walker (the costar whom Vin christened "Pablo" and who became like a brother to him), the actor explained during a 2015 Facebook livestream, per MTV News, "You see, the other guy in the photo is also named Paul...and although they look more alike, he is actually my twin brother."

In wishing his sister a happy 17th birthday in October 2021, the Stranger Things star called her "the best twin a brother could ask for," adding, "Here's to this duo for many more years."

The Jagged Little Pill artist was born 12 minutes after her brother in the Canadian capital of Ottawa.

Wade, a musician and yoga instructor, told the Winnipeg Free Press in 2010 that, Alanis' often angsty songs aside, "She can be as calm and Zen as the guru on top of a mountain and I can be as pissed off as her any other day, too. We kind of laugh sometimes when she's calm and I'm angry."

"To be honest, I have a twin brother, so I've had a built-in confidence always my whole life that, if anything, I always had my brother," Marissa shared on the podcast Proper Talk by Tonje in May 2021. "And my sister's a year younger and we were a really, really tight family, so I didn't have a lot of friend drama. And if I did, I would just retreat back up, and I always had my family, which always, most important."

The movies she and Giovanni have made together, 1998's Some Girl and 2001's According to Spencer, were also family affairs: Both were co-written by Marissa and count their mom, Gay Ribisi, as a producer. Marissa also pops up in Giovanni's pandemic-era Netflix series On the Verge, an ensemble dramedy created by Julie Delpy, which premiered in September.

The twins were born two months' premature to their chef mom and car dealership owner dad and grew up in Laurel, Miss. As of 2007, per the New York Times, Christopher was a lawyer living in Atlanta.

Lamenting the lack of witty best friend parts for women, noting that it was often a male buddy who got the funniest lines, Parker told Grantland in 2012, "I have a twin brother, so I was around guys like a sister. It was comfortable to me. It's weird, though, that it's still separate. It gets me down. What a bummer. 

Meet the Euphoria actor's twin brother: Jaden! "Nothing can come between us JDub," Javon wrote back in 2018. While Javon focuses on his acting, Jaden appears to be more into sports, sharing several photos of himself with Onward Athletics Baseball on Instagram.

Joselin did appear on a couple of episodes of Scrubs, where Judy's no-nonsense Nurse Carla ruled the roost, but otherwise the Bronx-born actresses have kept to their own projects–most recently P-Valley for Joselin and One Day at a Time and Search Party for Judy.

"It was my twin sister who wanted to be an actress," Judy told Shondaland in 2018. "She made my mom take her to acting class. My mother got so pissed because she made her go and the man wanted, like, $150 for pictures."

Neither sibling was bitten by the acting bug just then, with Joselin getting a master's in social work before heading back in front of the camera and Judy not really sure what she wanted until her later teen years. "But once it just clicked for me there was no turning back," she told Smashing Interviews Magazine in 2011.

Asked if anyone ever had a hard time telling her and Joselin apart when they were kids, Judy shared, "No, we're actually fraternal twins. We stopped looking alike in the fifth grade and now as we're past our fourth decade of existence, we're starting to look alike again so maybe that will happen yet." So, they weren't "that lucky" to be able to play pranks like identical twins could, "but maybe that's why we became actresses."

"I am a twin, but my brother and I aren't identical so it's not such a big deal," Joseph told The Guardian in 2016. "But when you share bunk beds and birthdays and a womb with someone, you have a special connection. It definitely feels different from the relationship I have with my other siblings—my twin and I are more connected. Jacob is a conservationist."

A land management superstar in the family's native England, Jacob was profiled by the New Yorker in 2020, the magazine calling the Fiennes "one of Britain's best-known bohemian families."

The twins are the youngest of six siblings, the eldest being Oscar nominee Ralph Fiennes.

When Xander needed a doppelganger on Buffy the Vampire Slayer for the episode "The Replacement," Nicholas had one at the ready—his own identical twin.

"He pays me $200 a week to sign autographs," Kelly quipped to People in 1999.

FYI, both brothers go by their real first and middle names, and their last name is Schultz.

The pair made their movie debut together playing twin call girls in the 1988 thriller Dead Ringers but only Jill decided to make a career out of acting.

"I would never want to subject her to my life because she' s inadvertently been the subject of such insanity solely by looking like me," the Crossing Jordan star lamented on Jacqueline's behalf in 2009. "She gets stalked by people who don't believe she's my twin. She'll very kindly say, 'I'm Jaq, her sister,' and they'll think she's lying. They think it's really Jill Hennessy just being really bitchy! People have yelled at her and just stormed away and I think it's my fault."

"She's a brilliant writer and television journalist in Toronto and is well known in Canada in her own right," Jill continued. "I do feel bad when I hear the occasional story of somebody who got a little irrational and maybe didn't have the best grip on reality, getting upset with her. It's hard not to take it personally and feel somehow responsible."

The resemblance can come in handy, though: In 1996, Jacqueline stood in for some of Assistant District Attorney Claire Kincaid's courtroom scenes on Law & Order while Jill was in Baltimore also playing Claire for an NBC cross-over event with Homicide: Life on the Street.

"Whenever I have any kind of dilemma in my life, my brother is the first person who I call and he always tells me the truth," Laverne said on TODAY in 2015 of the opera singer and composer who was born Reginald Lamar Cox. "He's kind of my moral compass in so many ways. He has been so unbelievable supportive and he's a brilliant artist in his own right."

M played his sister's character in flashback episodes taking place before Marcus had transitioned into Sophia on Orange Is the New Black.

"Our casting director found out that I have a twin brother, and she insisted that he should audition for the role," Laverne shared on HuffPost Live in 2013. "He auditioned, and he got the part."

"We were always super close and she was a lot more smiley, outgoing," fashion designer Charlotte said of her DJ sister on the 2020 docu-series Becoming. "I was a lot more quiet and serious."

Their older brother, musician Mark Ronson, joked to Harper's Bazaar in 2008, acknowledging their respectively busy schedules, "Not even on the high holiest of Jewish holidays do we all get together. But we get together individually whenever we can."

"Today Pati and I get to celebrate four decades of being alive on this amazing planet! How lucky I was to be born with my twin and best friend!" Gisele wrote on Instagram to mark their 40th birthday in 2020.

"She's married to an Italian count, lives in Italy and is busy raising her two children. Looking after the vineyard. Nice life, huh?" Eva quipped of Joy's trajectory to The Guardian in 2016.

Not that life's been such a slog for the Casino Royale and Penny Dreadful star, who's older by two minutes.

"Joy and I are very contrasting characters," Eva told the Daily Mail in 2008. "She never wanted to act, which was quite good because it would have been very competitive between us. We fought and were quite nasty to one another, but now we get on really well. She keeps all the clippings about me."

"Being a twin taught me the value of having a companion," Kiefer told The Guardian in 2018. "Every time I experienced something I could turn to my left and share it. When I was having my first child I said to my mother, 'My gosh you had two at the same time.' She said, 'Oh, sweetheart, it was fine. By the time you were 2 you were looking after each other.' She made it sound like she'd got a deal, which always made me laugh. My sister Rachel and I are incredibly close."

"I've had people tell me, 'Dan might be just a tidbit better-looking,'" Jon told W in 2008 of his identical twin. "'But don't worry,' they'd say, 'you're better with the ladies, more polite.'"

Still, the Napoleon Dynamite star added, "Dan gets fans coming up to him and when he tries to explain who he is, they don't believe him—they think he's being rude!—and they'll take the picture anyway. So most of the time he just pretends he's me."

And if you can't beat 'em, join 'em: The twins, together with their older brother Doug (altogether there are six Heder siblings), founded the production company Greasy Entertainment.

This story was originally published on Saturday, Dec. 18, 2021 at 4 a.m. PT.