03/06/2013 AT 06:40 PM EST
revealed a family secret on the radio.
"I have an older sister I've never known my whole life, who's in her 30s," Lovato, 20, told Long Island, N.Y., radio station, WBLI
, when asked if there's anything personal she'd like to share with her fans.
"She's my half-sister, but I talked to her for the very first time in my life around when I turned 20."
Calling from a "fancy" VIP airport lounge before a flight, Lovato – who didn't go into detail about which parent this sister came from – went on to say, "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.' I thought that was so incredible. So, I actually have three sisters."
One personal topic The X Factor
judge would not
address is romance.
When asked about her off
-and-on beau, Wilmer Valderrama
, the "Heart Attack" singer went mum when asked if she and the actor are back together.
"I just like to keep my private life like my life and stuff like that," she said. "And my friends and family and everything like that, I like to keep very sacred ... Unfortunately, no, I would not like to comment."