Yep, these two have been twinning (literally) since the very beginning. Thirty years later, they still love to coordinate their outfits — although these days, you're much more likely to spot them in matching black gowns and velvet slippers than in the pigtails and puff-sleeved pink rompers they favored back in their early TV days.

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Long before Alexa Chung spurred on the resurgence of overalls, MK&A donned denim bibs as Michelle Tanner in Full House. OshKosh B'Gosh sales soared.

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Admit it: You had no clue what a trench was (or how cool it could look) before these two swore an oath that they could solve any crime by dinnertime.

No single article of clothing got as much screen time in all of MK&A's straight-to-VHS movies — from Billboard Dad to Our Lips Are Sealed — as the spaghetti strap tank, which the twins often teamed with printed or embellished knee-length skirts. Honestly, their 1999 film Passport to Paris probably contains more shots of tank tops than it does of French landmarks.

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The twins' Two of a Kind era was marked by clompy footwear; sneakers for Mary-Kate (the sporty one!), and sandals or slides for Ashley.

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If you didn't tear photos of this MK&A hairstyle out of an issue of Teen People or YM to bring to the salon, were you even alive in the aughts?!

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Never has a long, chunky cardigan looked as cool as the ones MK&A wore in the opening credits for their short-lived series So Little Time.

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The twins' shared love of long, flowing silhouettes — which, of course, continues to this day — started here.

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Try as you might, you'll never find celebrities who love vintage more than Mary-Kate and Ashley. The sisters were sporting past-decade dresses, jewelry, and bags long before it was considered cool — and to this day, they still tend to dress in designer vintage for most red carpet events (unless they're repping The Row, of course). For the world premiere of New York Minute, Ashley chose vintage Givenchy, while MK went for a white lace dress from the '70s.

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In a 2014 interview with Elle, Mary-Kate admitted, "The truth is, I feel like I just learned to brush my hair last week." I don't doubt this. Sometime around mid-2004, it appears that both Olsens burned every hair-taming tool in their homes, never to pick one up again. Over the years that followed, they'd go on to push half-up topknots, gelled ponytails, and even sopping wet, straight-out-of-the-shower strands.

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In September 2004, Mary-Kate and Ashley started as freshmen at New York University. Somewhat coincidentally, this was also when they adopted their now-signature bug-eyed shades as their paparazzi armor of choice.

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Around the time they matriculated at NYU, the sisters also began running around the city in long, heavy layers, floor-sweeping skirts, and super-sized scarves. Mary-Kate was particularly fond of the dumpster-dressing look, and inspired an entire New York Times piece dedicated to her "Bobo" — or "bohemian bourgeois" — style. Some (okay, many) mocked their outfits; others, bored with the aggressively sexy and logo-laden looks so popular at the time, found them refreshing.

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The Olsens were fond of XXL-sized bags in general during this era, but it was this Nicolas Ghesquière design that got the most play. The twins owned the motorcycle-inspired, lariat-adorned carryall in multiple colors, but Mary-Kate was most frequently spotted with the mint green version seen here. In MK's January 2006 W cover story, writer Marshall Heyman points out, "It's so dingy, covered with stains, pen marks and even a chewed-up piece of gum, it looks almost gray." Olsen's reply? "It explains my life."

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I'd like to think of the twins' yearlong love affair with Western footwear as a subtle callback to their 1994 straight-to-video classic How the West Was Fun. But maybe that's just me.

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Sure, Starbucks has been serving coffee to celebrities (and regular folks!) across the country for decades. But it wasn't until the sisters Olsen started toting their Venti lattés absolutely everywhere that the mermaid-stamped cup went from caffeine vehicle to bona fide accessory.

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Go ahead and credit Sarah Jessica Parker with making Manolo Blahnik a household name, but it's Mary-Kate and Ashley who made women across the globe covet Christian Louboutin's red soles. In the mid-aughts, they practically lived in the French designer's stacked-wood stilettos.

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What's a mini mogul with teeny-tiny arms, an eclectic sense of style, and an overflowing collection of bracelets to do? Wear them on her upper arms instead of her wrists, of course! Man Repeller's Leandra Medine may have coined the term "arm party," but Mary-Kate Olsen was pushing her bangles up to (and often even above) her elbows before anyone else.

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Following her departure from NYU, Mary-Kate traded her maxiskirts and shredded denim flares for black opaque hosiery paired with oversized flannels and belted tunics. Sorry, Blair Waldorf.

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Olsenologists likely remember 2006 as the year when Mary-Kate Olsen basically stopped wearing any color other than black. She became especially fond of floor-dusting, bell-sleeved dresses Morticia Addams would love, and often accented them with a wide belt (more on that below) or a mishmash of long necklaces. Interestingly, it wasn't until a year or so later that Ashley dabbled in this Elvira-approved look, too.

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Okay, so maybe we can't quite credit MK&A for making T-shirts a thing — but they were largely responsible for making us rethink the way we shop for and style our tees. Consider the fact that between their CFDA Award-winning collection The Row and more affordable StyleMint brand (RIP), they launched their design careers around the goal of creating the perfect T-shirt.

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Leave it to these trendsetting twins to take a questionable in-da-club classic — the body-con miniskirt — and turn it into something stylish that you'd want to wear every day. In the late aughts, the pair frequently wore these tight little skirts with slouchy tees and boyfriend-style button-ups to make them feel less vampy and more relaxed. They often DIY'd the look, too; in an August 2007 Marie Claire interview with Ashley, writer Lucy Kaylin notes, "That black mini she's wearing? It's actually a Wolford bodysuit pulled down — she shows me the strappy part tucked in around her waist, under her shirt." And in a piece on Mary-Kate in Harper's Bazaar from that same year: "She is wearing a nautical striped T-shirt (her mom's from the '70s), tucked into two black Wolford slips rolled down and turned into a tight, Robert-Palmer-video-style mini." Eventually, they produced a similar style in leather for their line The Row (seen here on Ashley).

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There's no doubt about it: MK&A are completely obsessed with their collection of fluffy coats, chubbies, and stoles. And when you're an Olsen, there's no need to save your finest furs for a special occasion; even a casual lunch date or bodega run is reason enough to break out that mink.

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Before fellow famous Alaïa fan Michelle Obama put a White House-worthy spin on his wares, the Olsens wore the designer's wide statement belts absolutely everywhere, from James Taylor concerts to the Met Gala.

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Those Le Dix bags aren't the only Balenciaga accessories the girls have fallen for. Several years later, they started wearing the French label's perilously high footwear nonstop. Mary-Kate favorited the edgy harness ankle boots; Ashley, the cork-soled sandals (although MK actually borrowed them for the 2007 Met Gala). Lower-priced knockoffs of both styles popped up in no time.

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But if you thought that was the only footwear trend the Olsens jump-started in 2007, guess again. They were also largely responsible for making high-heeled gladiator sandals a thing. Ashley favored pairs by Aläia, while Mary-Kate was often spotted in a wedge style from (who else?) Balenciaga.

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While everyone else was taking style cues from the aforementioned Blair Waldorf and her seemingly endless collection of prim and proper headbands, the Olsens debuted a more avant-garde take on the trend. From Prada turbans to Marc Jacobs velvet bands, if it came straight off a runway, MK&A were down to try it.

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I'm not quite sure why Mary-Kate and Ashley feel the need to tote around massive carryalls (sometimes more than one!) everywhere they go — or, more importantly, what they keep in there. Rolled-up yoga mats? Empty Starbucks cups? Old issues of Mary-Kate and Ashley magazine?!

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Sure, we all laughed when Ashley started wearing these German cork-soled sandals everywhere — but sure enough, two years later, they were fashion's (admittedly unlikely) favorite shoe.

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Perhaps because there are only so many pairs of super-huge sunglasses a woman can own, Mary-Kate and Ashley started sporting smaller, John Lennon-esque shades around this time. They also created multiple versions of the eyewear style for The Row.

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Shortly after the girls started sporting anklets in fashion week's front rows, they teamed up with jeweler Ileana Makri on a capsule of gold, gemstone-adorned versions for The Row's spring 2012 collection. The price for the twins' take on the trend? $4,000 — or $8,000, really, since you obviously had to wear one on each ankle à la Ashley.

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Chalk it up to platform fatigue, but the twins eventually swapped their towering sandals and booties for more ankle-friendly (and geriatric-approved) options. Nowadays, it's still far more common to spot MK&A in kitten-heeled slingbacks, pointy-toed mules, or Chanel ballet flats than in super-high heels.

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