Kerry Washington on Discovering Her Dad Is Not Her Birth Father

Kerry Washington is opening up about a startling revelation regarding her parents. 

In her new memoir, Thicker Than Water, the 46-year-old Scandal star shares that she recently learned that her father, Earl Washington, is not her biological father. It’s news that sent her on her current journey of self-discovery.

“It really turned my world upside down,” Washington tells PEOPLE in next week’s issue.

The actress explains that she discovered the family secret shortly after she told her parents she was planning to appear on Henry Louis Gates Jr.’s Finding Your Roots, a PBS series where celebrities learn about their ancestors through DNA testing. 

Having held onto the secret for decades, Washington’s mom, Valerie, a professor, and dad, Earl, a real estate agent, had a private conversation with Gates, who told them it was always best for families to discuss such revelations privately prior to filming. What came next, says Washington, was a text message from her parents inviting her to a family sit-down in the spring of 2018.

“When I got this information, I was like, ‘Oh. I now know my story,'” says the star, who recalls feeling a sense of relief at the news after long feeling her parents were keeping things from her and that something was missing. “I didn’t know what my story was, but I was playing the supporting character in their story.”

Washington says she kept her calm and asked a lot of questions while trying to give her parents grace in what was clearly a difficult moment for them. She learned that they’d opted to use an anonymous sperm donor to help conceive after struggling with fertility issues. They admitted they had all but decided never to tell her.

“I think that dissonance of like, ‘Somebody is not telling me something about my body.’ made me feel like there was something in my body I had to fix,” she says of struggling for years with anxiety, self-esteem issues, and an eating disorder when she was young. She now feels those might have been symptoms of subconsciously sensing her parents’ secret.

Armed with the new information, Washington says it led her to want to tell the world her true story —and Thicker Than Water is the result.

“This is really kind of me working to understand my life up until now, given this new information that I have that, in many ways, felt like sort of the missing puzzle piece,” she says.

For more on Kerry Washington’s life story and new memoir, pick up a copy of PEOPLE, on stands Friday.

“My parents were not thrilled about me writing this,” she notes, though the couple grew supportive throughout the process. But, says the star, “this really is a book about me. I now get to step into being the most important person in my life.”

The experience ultimately added a new layer to Washington’s bond with her parents.

“I really started to have so much more love and compassion and understanding for my parents,” she says. “Taking this deep dive into our family history made me put myself in their shoes and think about the things that they’ve had to navigate and what they’ve been through and what they’ve sacrificed. And it really made me feel closer to them.”

The news of her paternity is just one of many revelations in Washington’s memoir, which will hit bookshelves on Tuesday, Sept. 26.  According to a press release, Washington’s memoir will give readers “an intimate view into both her public and private worlds — as an artist, an advocate, an entrepreneur, a mother, a daughter, a wife, a Black woman.”

“Writing a memoir is, by far, the most deeply personal project I have ever taken on,” Washington told PEOPLE in January. “I hope that readers will receive it with open hearts and I pray that it offers new insights and perspectives, and invites people into deeper compassion — for themselves and others.”

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Kerry Washington’s memoir, Thicker Than Water, is available Sept. 26 wherever books are sold.