Kim Kardashian's Throwback Photo Of North & Penelope Shows How Close They've Always Been

Handout/Getty Images Entertainment/Getty Images

My, how they've grown. Kim Kardashian's throwback Instagram photo of North and Penelope shows the cousins truly have always kept up with each other. "Look what I found," she captioned the shot of her and Kanye West's 5-year-old and the 6-year-old daughter that her sister Kourtney Kardashian shares with ex Scott Disick. "They were so small."

Within the first 10 hours that Kim uploaded the pic, her post racked up upwards of 1.4 million likes and more than 5,400 comments. Among those adding their thoughts in the comments section, of course, was the young girls' aunt, Khloé Kardashian. Aunt Koko raised a few eyebrows when she wrote, "Hahaha the Diddy crop!!!!" under the snap.

For reference, rapper Sean "Diddy" Combs has become infamous for cropping people — including Kendall and Kyle Jenner, one time — out of photos before posting them on social media. (He later claimed that what became known as the #DiddyCrop wasn't intentional, by the way.) So fans naturally wondered who exactly Kim cropped out of the photo. That may well remain an unsolved mystery, however.

Just one day early, Kim shared another sweet photo of herself with North, Penelope, and Kourtney, adding the caption: "Spring Break is over 😭📖📚✏️" While the fashion-forward cousins were both twinning in matching school uniforms, they added their own personal style twists, with North opting for Converse high-tops, while Penelope sported a pair of loafers. Kourtney and Scott's girl's shoes were reportedly Gucci and retailed for almost $400. "P is such a little beachy lady," Kendall commented on her niece's look.

The cousins have been tight practically from birth. "Thankful for our babies being besties 👯," Kim captioned a November Instagram photo of the duo. One year earlier, Penelope even asked North some questions for her 2017 Interview feature.

After Penelope inquired about joint activities from building neighboring tree houses and bringing her puppy to a sleepover during their interview, she finally asked if they could have a baking party together. North's response? "We can make rainbow princess cake!"

North was also recently the star of her mom's social media accounts when she sang with a gospel choir at dad Kanye's Sunday Service on April 7. In one of Kim's Twitter videos, the youngster adorably grabs the mic and really steals the show. "Had to move up front and center 😂⭐️," she tweeted.

North, who's already a big sister to Saint, 3, and 1-year-old Chicago, is about to have another playmate as well. In January, Kim and Kanye announced that they are expecting their fourth child, a son, via surrogate. Kim confirmed the news — adding that the baby is due “sometime soon” — during a joint appearance with Kourtney and Khloe on Bravo's Watch What Happens Live.

The new baby will arrive just as North has begun bonding with Saint — though Kim had some initial concerns that would ever happen. "I do worry about them getting along, because for my sisters and I, we were just so close growing up and obviously still are," she said in recent interview with Elle. And I want them to be, too! But they’re starting to get closer now that she can include him in her jokes."

With any luck, North will be as close with her new brother as she is with Saint and, of course, Penelope, too.