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Asked by WBLI radio station if she had anything she wanted to share with fans, Demi opened up about the surprising family revelation.
"I just got to know ... I have an older sister that I've never known my whole life," the "Heart Attack" singer explained. "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 [in August 2012]."
During their first conversation, Demi says she wondered why the two hadn't connected earlier.
"I asked her, 'Why haven't you ever contacted me?'" Dem shared. "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.'"
A relationship is something that Demi says she and her new half-sister are excited to work on.
"I thought that was so incredible," Dem said. "So I actually have three sisters, that I didn't know until this year."
No other information was available on Dem's half-sibling, but she joins the family consisting of Demi's other two sisters, 25-year-old Dallas Lovato and 11-year-old Madison De La Garza.
The radio station also tried to get details from Demi about her love life, asking her if she wanted to talk about reportedly reuniting with actor Wimer Valderrama on Valentine's Day, but she was more guarded on that topic.
"I actually like to keep my private life, love life and stuff like that ... I like to keep it very sacred," she "X Factor" judge explained. "There are some things you just have to keep to yourself. Unfortunately, I would not like to comment."
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