Demi Lovato's Christmas list just got one name longer.

The 20-year-old singer just revealed she has a sister she never knew existed until 2012!

"I have an older sister that I've never known my whole life," she told WBLI Radio earlier today. "She's in her 30s. She's my half-sister. I talked to her for the very first time in my life around when I turned 20."

FYI: Demi turned 20 last August.

"I asked her, 'Why haven't you ever contacted me?'" Lovato continues. "She said 'Well, because I never wanted you to think that I wanted anything from you. So I've just been waiting to see if you wanted a relationship.'"

Demi already has two other sisters (that she knows about), 25-year-old Dallas and 11-year-old Madison De La Garza, who played one of Eva Longoria's daughter on "Desperate Housewives."

Pretty surprising news to learn after 20 years, isn't it? See more stars and their siblings above.

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