Joan Collins and Percy Gibson Make Their 21-Year Marriage Work with Scrabble — and Separate Bathrooms

Joan Collins has achieved several lifetime’s worth of accolades throughout her legendary Hollywood tenure, but the Dynasty star is particularly proud of a non-career achievement: her decades-long marriage to Percy Gibson.

Collins tells PEOPLE in this week’s issue that there are a few elements that have kept her marriage going strong for so many years, and they range from shared hobbies to separate facilities.

To the actress, success lies in keeping a balance in her relationship, which she says she and Gibson have worked out to be “separate bathrooms and the same bedroom.”

“First of all, Percy and I were working together and we became great friends,” Collins, whose new memoir, Behind the Shoulder Pads: Tales I Tell My Friends, is nowavailable to purchase, explains. “We found we had a lot in common. We like the same things. We like doing the same things.”

As for what those “same things” are, Collins, 90, says, “We both adored the theater, and particularly musical theater. We love reading. We love playing cards or playing Scrabble. Neither of us are particularly outdoor[sy] people. You know, he doesn't go running out to football games. And we love going to the theater and films and we just got along.”

The combination of those mutual interests led the Golden Globe winner to conclude that she and Gibson are in “the same blood group.”

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Collins and Gibson’s story began when the former starred in a play managed by Gibson's company in 2000. She had been married four other times before their meeting, but addressed the distinction between her relationship with Gibson from past loves in her 2011 memoir The World According to Joan. She said at the time that she "kissed a lot of frogs before I found my prince.” By 2002, the couple officially wed and have been together ever since.

When it comes to critics who have called out the 32-year age gap between her and Gibson, 58, Collins makes it known that the naysayers don't affect her.

“They don't do it in England anymore because everybody knows how happy we are together,” she explains. “And, you know, age is — as far as we're concerned — just a number, and that's the way that we both feel.”

She doubles down , telling PEOPLE, “Obviously, we talked about it before we got married, but it isn't in the slightest importance.”