From their early days on Full House, where they played the same girl, Mary-Kate and Ashley have taken twinning to whole new extremes.
Mary-Kate and Ashley Olsen in West Hollywood, California, September 1994. Photo by Ron Galella, Ltd./WireImage.
Four years later, they still coordinated looks — and it didn't stop here.
Mary-Kate and Ashley Olsen in New York, New York, January 1993. Photo by Ron Galella, Ltd./WireImage.
What does one wear to an *NSYNC album release party? Mary-Kate and Ashley have an idea.
Mary-Kate and Ashley Olsen in West Hollywood, California, July 2001. Photo by Ron Galella, Ltd./WireImage.
The twins continued to do their thing at the 2002 Vanity Fair Oscar party.
Mary-Kate and Ashley Olsen at the Vanity Fair Oscar Party in Los Angeles, California, March 2002. Photo by Gregg DeGuire/WireImage.
In the transition from television stars to full-fledged movie stars, the Olsens also started to discover their personal style.
Mary-Kate and Ashley Olsen at the premiere of Charlie's Angels: Full Throttle in Hollywood, California, June 2003. Photo by Getty Images.
In '20s-inspired looks for the premiere of their film New York Minute, Mary-Kate and Ashley branched out from straight-up matching looks, venturing into careful coordination.
Mary-Kate and Ashley Olsen in Los Angeles, California, May 2004. Photo by Kevin Winter/Getty Images.
Their hair styles have undergone as drastic a transformation as their personal style — around 2005, both girls played with kinky curls, a very early-'00s move.
Mary-Kate and Ashley Olsen at the 12th annual amfAR Gala in Cannes, France, May 2005. Photo Pascal Le Segretain/Getty Images.
In 2006, Mary-Kate and Ashley started The Row, marking them as designers to watch as well as red carpet stars. They continued to embrace eclectic, bright styles, but that would soon change.
Mary-Kate and Ashley Olsen at the CFDA/Vogue Fashion Fund Awards in New York, New York, November 2006. Photo by Rabbani and Solimene Photography/WireImage.
The Olsens made a quite seamless transition from red carpet to front row, appearing in chic and understated ensembles at shows like Jenni Kayne, here. They have also earned a bit of ill will from PETA for their apparent love of fur, but that doesn't seem to have stopped them.
Mary-Kate and Ashley Olsen front-row at Jenni Kayne during New York Fashion Week Fall 2007. Photo by Jamie McCarthy/WireImage for Jenni Kayne.
In addition to The Row, the Olsens also design a sister label, Elizabeth & James — here, they wear monochrome ensembles from the line, proving they're putting their color phase behind them.
Mary-Kate and Ashley Olsen at the CFDA Fashion Awards in New York, New York, June 2007. Photo by Getty Images.
For a time, both sisters center-parted their hair; Mary-Kate has since claimed the style as her own, though both often apear with beachy waves, as here.
Mary-Kate and Ashley Olsen, both in Diane Von Furstenberg, at the Metropolitan Museum of Art Costume Institute Gala for "Superheros: Fashion and Fantasy" in New York, New York, May 2008. Photo by Getty Images.
Mary-Kate has been called the more daring of the two, but here, it's Ashley who opts for the plunging neckline and higher heel. Though they've always coordinated their red carpet looks, they allow their personal style to peek through the all the twinning.
Mary-Kate, in Lanvin, and Ashley Olsen, in Christian Lacroix, at the Elle Style Awards in London, England, February 2010. Photo by Samir Hussein/Getty Images.
We can't fault any part of this Yves Saint Laurent duo. Chic, elegant, a little unusual, it's the Olsens at their sartorial peak — and it's not even their own design.
Mary-Kate and Ashley Olsen at the Metropolitan Opera premiere in New York, New York, March 2011. Photo by Rob Kim/FilmMagic.
For the 2014 Met Gala, both Olsens selected vintage gowns — for Ashley, left, Gianfranco Ferré, and for Mary-Kate, right, Chanel. The Olsens consistently prove they know their stuff when it comes to fashion.
Mary-Kate and Ashley Olsen at the Metropolitan Museum of Art Costume Institute Gala for "Charles James: Beyond Fashion" in New York, New York, May 2014. Photo by Getty Images.
Though in previous years they've often rocked vintage ensembles, at this year's Met Gala, the twins wore their own designs.
Mary-Kate and Ashley Olsen in The Row at the "Manus x Machina: Fashion in an Age of Technology" Costume Institute Exhibition Gala in New York, New York, May 2016. Photo by Getty Images.
They've now recruited a third — sister Elizabeth, for whom their Elizabeth & James line is named, is just as chic as her elder sisters.
Mary-Kate and Ashley Olsen with Elizabeth Olsen, all in The Row, at the CFDA Fashion Awards in New York, New York, June 2016. Photo by Getty Images.