Mary-Kate and Ashley Olsen describe their relationship as a marriage

Mary-Kate and Ashley Olsen are opening up to WSJ. Magazine ahead of the launch of their fashion line, The Row's first menswear collection.

The fraternal twins, 32, who are famously private about their lives, talk about their personal and business relationship in the rare interview.

"It’s been 32 years of learning how to communicate," Ashley tells the mag, who says their relationship is "a marriage and a partnership. We have had ups and downs."

"We do everything together," she says, with Mary-Kate adding, "We came out of the womb doing that."

And they've certainly come a long way since their adorable outfit-matching days as child actresses.

Following their role as Michelle Tanner on the '90s sitcom Full House, the Olsens became a household name. In 2005, the stars shed their Hollywood life and turned their attention to creating a fashion line (without formal training).

While most celebs use their names to their advantage when creating their own brands, the Olsens did the complete opposite. The result became The Row, a luxury line that values quality over quantity. They also co-founded Elizabeth and James, a mid-level priced line that plays with more feminine, trendy designs compared to its predecessor.

"We’re not product pushers,” Ashley says. "I don’t know if it’s because of the way we grew up—we just don’t like talking about ourselves or talking about what we’re doing... It’s not really our approach.”

This quiet, minimalist yet impactful aesthetic of their clothes and accessories catapulted the twins as serious designers, who have gone on to earn accolades and obsession from the fashion crowd. They won the CFDA Womenswear Designer of the Year in 2012 and Accessory Designer of the Year Award in June.

With their sleek outerwear and separates largely inspired by the borrowed-from-the-boys look, along with a constant focus on impeccable tailoring and craftsmanship, it was only natural for them to transition into menswear. Plus, many of their customers, friends and family were asking for it!

In 2016, the twins began the process of researching and testing techniques, fabrics and fits for the perfect suit.

The Row menswear suits
Ethan James Green/Courtesy of WSJ. Magazine

Mary-Kate describes the range as being "for the husband" of The Row's female customers. She also mentions her husband, French banker Olivier Sarkozy, 49, always wears suits and we predict we'll definitely see him sporting his wife's new designs for business meetings.

In a time when streetwear and fast fashion reign, the Olsens' newest launch -- which will include denim pieces and knits in addition to suiting -- is set to bring back elevated simplicity to menswear (in lieu of the hoodies and ripped jeans we often see now) courtesy of hand-stitched linings, hidden branding, precise fits and clean, unfussy silhouettes that will truly stand the test of time.

"It’s funny, because this is more of a risk than putting words on a T-shirt," Mary-Kate says. "Who knew that black, gorgeous, perfectly fitted suits would be a risk?"

Although the talented duo is inseparable, Ashley reveals she's open to moving back to Los Angeles despite her sister being tied to New York.

Their line is positioned to foray into online sales in 2019, which the twins have consciously avoided since The Row's debut. They are also considering launching skincare products, small leather goods for women and opening stores in Europe, in addition to their Upper East Side and Melrose Place locations.