Arguably the most famous twins of all time, Mary-Kate and Ashley defined the It Girl for a Y2K generation. From Full House to a string of cult-favorite movies, the duo helped create and confirm a cultural fascination with twindom. After an era of aspirational partying that became the backbone of Tumblr, the Olsen twins graduated to the upper echelons of fashion with creation of The Row, becoming synonymous with timeless style, oversized sunglasses, and bowls and bowls of cigarettes.

It Girl sisters and supermodels? Bella and Gigi Hadid have graced many a runway and magazine cover, but remain down to earth regardless of their immense status. Both sisters ride for their Palestinian heritage and are candid with the public about their struggles. What more could you want?

Is there a single mother on this planet more proud than Miss Tina Lawson? Beyoncé and Solange have effectively dominated the music industry for the last couple of decades. Their accolades from this summer alone are enormous: Clubs are blaring RENAISSANCE nonstop, and Solange just became the first Black woman to compose for the New York City Ballet. But the Knowles sisters know that what’s even stronger than success is loyalty — we all know something serious went down in that elevator.

Aly and AJ have been steadily growing their devoted fanbase after gracefully exiting the Disney conveyer belt after starring in Phil of the Future and Cow Belles. Now, they’ve revamped the mid-aughts power jam “Potential Breakup Song” for a TikTok audience, along with an excellent first album since 2007.

It’s rare for not one, but two child stars to make it out unscathed, but Dakota and Elle have been quietly racking up meaty roles without scandals for years. Elle and Dakota made their film debut at the same time, with Elle playing a younger version of Dakota in 2001’s I Am Sam; Dakota went on to charm us to tears in Uptown Girls while Elle took on indies like Sofia Coppola’s The Beguiled. Apparently they still live around the corner from each other and say they balance each other out. "It's a very rare and special thing that we both do this," Elle recently told E! Everyone say awww.

So famous for being sisters they had a show called Sister, Sister where the play identical twins who reunite after growing up separately, I can’t think of Tia and Tamera without the theme song, which they even sang together. “Sister sister/ I got my own mind/ I do my own style in my own time,” is a 90s anthem for all sisters who are like friends — and friends who are like sisters.

Paris and her mellower counterpart Nicky — the ying and yang of party girl heiresses turned moguls — were a fixture of nightlife in the mid-aughts. Nicky was always the more low-key one, famously telling Paris when she would call to complain about being overworked that she’s greedy and can’t turn down a check. If there’s anyone who needs a sister to be straight with you, it’s a party girl heiress!

The fame of the Kardashian-Jenners is built on the back of sisterhood. They literally became famous for being a family, and even though they’ve become more and more out of touch with every brand sponsorship and dollar sign that gets added to their collective net worth, part of what continues to draw us in is their family relatable dynamics: the stupid fights, the slog of logistics they discuss on speakerphone, and their boundless love.

While older sister Paloma has quickly become a runway staple, younger sibling Ama is following in their big sister’s footsteps — from covering i-D to starring in Calvin Klein’s Pride campaign.

Like many a storied It Girl before them, Simi and Haze are internationally known DJs. Plus, there’s the whole twins-moonlighting-as-models thing and how their inner circle doubles as a wild Hollywood A-list rap sheet.

The Hemingway sisters are It Girls by way of art. Off the runway, Dree is an as indie film darling, while Langley is best known for her photorealistic pencil drawings.

As the offspring of Lionel Richie, Nicole and Sofia were destined for It Girl-dom from the jump. Nicole essentially created reality television as we know it (alongside best friend, Paris) and Sofia is poised to take the tabloids and catwalks by storm.

It Girls may help us on a spiritual, aesthetic, or collective level, but Devon and Sydney do all that while helping on a practical level — by protecting our beloved phones. The Wildflower Cases founders make extra cute phone cases by day, and light up the fashion world by night.