Today marks Mary-Kate and Ashley Olsen‘s 28 birthdays—and if it’s even possible, it seems these two actresses-turned-fashion-icons get chicer with each passing year. They might look nearly identical (remember, they’re actually fraternal twins!), but these dual mini-moguls couldn’t be more different in terms of their personal styles. While Ashley adores streamlined, minimalist silhouettes elevated with ultra-luxe accessories, Mary-Kate‘s all about a bohemian, rock ‘n’ roll vibe that’s heavy on the vintage.
Still, MK & A do share one important thing, style-wise: together, they’ve been responsible for more fashion and beauty trends than you might think. Don’t believe me? Click through above to see 17 trends we can thank Mary-Kate and Ashley for starting, from Christian Louboutin’s wooden-soled pumps to second-day hair to, yes, the Starbucks-cup-as-accessory.