Sia reveals that she's a grandmother: 'They call me Nana'

• Sia has two grandchildren, she revealed on Tuesday's episode of Zane Lowe's Apple Music show.
• "My youngest son just had two babies," she said, referring to one of the two teenage sons she adopted after they aged out of the foster care system.
• The musician added that her grandchildren call her "Nana."

Sia recently became a grandmother, she revealed during Tuesday's episode of Zane Lowe's "Beats 1."

"My youngest son just had two babies," the musician, 44, said, adding, "I'm just immediately horrified. No, I'm cool."

Though Sia didn't share her grandchildren's exact ages, she said that they already have a nickname for her.

"They call me 'Nana,'" she said. "I'm trying to get them to call me 'Lovey,' like Kris [Jenner]. I'm like, 'Call me Lovey.'"

Her announcement came one month after the singer revealed that she adopted two sons that had aged out of the foster care system.

"I actually adopted two sons last year. They were 18. They're both 19 now. They were aging out of the foster care system, and I love them," she said on SiriusXM's "The Morning Mash Up" on May 20.

During her interview with Lowe, Sia spoke about her sons' experience growing up in foster care before she adopted them.

The musician explained that by the time she adopted her sons, they had been moved to 18 different locations through the foster care system. Like the thousands of children in the system, Sia's sons had a lower chance of being adopted as they grew older.

According to the National Foster Youth Institute, 20% of children who reach 18 years old in the foster care system will become instantly homeless. And out of the 23,000 children that age out of the system annually, one out of every two will be employed by the time they're 24.

"I'm a little bit jaded now after investigating the foster system as much as I have done in the last year," she said. "It's completely corrupt. It's failing us."

After bringing her sons home, a transition she described as a "roller coaster," Sia explained that both of them have participated in programs to treat trauma.

"One recently came out and he's just blossoming, and it's the light of my life. I love him so much," she said, sharing that her youngest son is still currently in treatment to process past trauma.

"You can't force anyone. Trauma has to come out when you're in a safe environment and when you're ready, psychologically ready, so I'm just trying to do my best for them."