Demi Lovato has a new secret to share. The singer and X Factor judge, 20, made an unexpected revelation about her personal life during a recent radio chat on WBLI. "I have an older sister I've never known my whole life, who's in her 30s," the "Skyscraper" singer told the Long Island, New York station, which she called from an airport lounge. "She's my half-sister, but I talked to her for the very first time in my life around when I turned 20."

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Lovato didn't reveal her uncovered sibling's name -- or whether it's her mother or father's child -- but said of the encounter, "I asked her, I said, 'Why haven't you ever contacted me?' She said, 'Well, I never wanted you to think I wanted anything from you. So I've just been kind of waiting to see if you wanted a relationship.'"

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The star noted: "I thought that was so incredible. So, I actually have three sisters." (The Camp Rock star has two sisters Dallas and Madison.)

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During the call, Lovato declined to get into detail about her love life and her current status with on-again, off-again beau Wilmer Valderrama. The couple spent Valentine's Day together at Takami Sushi & Robata Restaurant in downtown L.A.. "They ordered almost everything on the menu, but they didn't touch it for at least an hour," a source revealed to Us Weekly. "They stared into each other's eyes the whole time."

This article originally appeared on Demi Lovato: I Have a Secret Half-Sister