Thursday, April 10 is National Siblings Day, and already #HappyNationalSiblingsDay is trending on Twitter and Instagram, with people expressing love for their siblings, both born and chosen.

The History of National Siblings Day

National Siblings Day is celebrated the 10th of April and was founded by Claudia Evart, a paralegal in Manhattan, who began the celebration in honor of her two siblings who died young. The date of April 10 is special to Evart, as it marks her late sister’s birthday.

“Like many, I have these pictures of my brother and sister, who are both gone, but remain with me daily, not just in these pictures, but in my daily thoughts and in my heart. I lost both of them in tragic accidents, making me understand the everlasting bond we have with our siblings,” Evart is quoted as saying on the Siblings Day Foundation website.

Evart began the Siblings Day Foundation to help spread the holiday and has successfully spread to states all over the country. The federal government does not yet recognize the holiday, though it is called National Siblings Day. However, both Presidents George W Bush and Bill Clinton signed a Presidential Message during their time in the White House recognizing the holiday. A Presidential Proclamation is still needed for the holiday to be officially established.

'Game of Thrones' And More Celebrate National Siblings Day

As National Siblings Day celebrations take over social media, fan favorite siblings from various films and TV shows have also been celebrating on Twitter. Game of Thrones posted a photo of the show’s most notorious siblings, twins Cersei (Lena Headey) and Jaime Lannister (Nikolaj Coster-Waldau), writing, “Happy National Siblings Day to all in the realm.”

Social change organizations are also using the popular hashtag to promote their causes.

Finally, First Lady Michelle Obama also got in on the fun, posting a ‘Throwback Thursday’ photo of her and her brother.

Happy National Siblings Day!

– Olivia Truffaut-Wong