For the last few years, every April 10th, National Sibling Day is celebrated. From Instagram to Twitter to TikTok, social media feeds are flooded with pictures and videos of users with their siblings. 

(Photo credit should read ROBYN BECK/AFP via Getty Images)
(Photo: ROBYN BECK/AFP via Getty Images)

Although National Siblings Day is not a federal holiday, former Presidents Bill Clinton, George W. Bush, and Barack Obama have all issued letters recognizing the day, according to the Siblings Day Foundation.

In honor of the special day, let's celebrate these famous duos who are siblings, but you may not have known were related in real life! 

Blake Lively and Robyn Lively

(Photo by Taylor Hill/WireImage)
(Photo by Taylor Hill/WireImage)

Robyn Lively starred in the cult classic film, 'Teen Witch,' later landing a major role on the hit show 'Twin Peaks.' In 2017, during an interview with 'Access Hollywood,' the sisters shared that they are "best friends." 

Despite their 15-year age age, they said their bond is "everything."

Debbie Allen and Phylicia Rashad

 (Photo by Ron Sachs - Pool /Getty Images)
(Photo by Ron Sachs - Pool /Getty Images)

Phylicia Rashad, who famously starred on 'The Cosby Show' as Clair Huxtable, the family's beloved matriarch, is the big sister to her talented sibling, Debbie Allen.

Allen, born January 16, 1950, went on to become a trailblazing dancer, actress, and television producer. 

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Cuba Gooding, Jr. and Omar Gooding

(Photo by Rob Latour/Variety/Penske Media via Getty Images)
(Photo by Rob Latour/Variety/Penske Media via Getty Images)

Between the two brothers, the 'Radio' actor was the first to follow his dreams to act in the early 1980s, signing with an agent. 

His sibling Omar, who starred in 'Baby Boy' (2001) and series regular roles on Nickelodeon's 'Wild & Crazy Kids' and 'Smart Guy' in the '90s, was discovered by talent scouts while dropping off a script to his big brother.

Their father, Cuba Gooding Sr., was the former lead singer for The Main Ingredient

Kate Hudson and Oliver Hudson

 (Photo by: Weiss Eubanks/NBCUniversal via Getty Images)
(Photo: Weiss Eubanks/NBCUniversal via Getty Images)

If having famous parents (Goldie Hawn and Bill Hudson) wasn't enough, these Hollywood stars are also family — in real life!

The celebrity siblings even work together under the banner of Kate's activewear brand Fabletics. 'The Bride Wars' star's big brother Oliver spearheads the men's division, FL2.

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Zooey Deschanel and Emily Deschanel

(Photo by Dan MacMedan/Getty Images)
(Photo by Dan MacMedan/Getty Images)

Emily, best known for her role on Fox's 'Bones' from 2005 through 2017, is the elder sister to actor, singer, and songwriter Zooey. She is best known for starring on the Fox comedy 'New Girl.'

Caleb Deschanel, the sister's father, is an Oscar-nominated cinematographer. Their mother, Mary Jo Deschanel, is also an actor, known for her recurring 'Twin Peaks' character Eileen Hayward.