For years, actresses Liv Tyler and Mia Tyler had no idea they were sisters.

The siblings, who are 18 months apart in age, recalled meeting for the first time and learning about their familial connection in a recent episode of the "Sibling Revelry with Kate Hudson and Oliver Hudson" podcast

Liv and Mia Tyler share the same father -- Aerosmith's Steven Tyler -- but have different mothers.

"We're half [sisters]," Mia Tyler, 46, explained to host Kate Hudson. "But we don't say half because what does that mean?"

"I call you sister," Liv Tyler, 47, agreed.

As a child, Liv Tyler said she was raised by her mother -- singer and former model Bebe Buell -- and her extended family in Maine and thought her mother's boyfriend at the time, musician Todd Rundgren, was her father, since he played a father role in her life.

Mia Tyler, meanwhile, said she had grown up in New Hampshire with her parents -- Steven Tyler and Cyrinda Foxe -- who were married for about 10 years.

Liv Tyler said that when she was about 9 years old, she attended an Aerosmith concert with her mom. It was there, she said, when she first noticed another young girl -- Mia Tyler, who was about 8 at the time -- who looked like her.

"I just remember standing there watching [Guns N' Roses open for Aerosmith], looking and seeing this girl who looked exactly like me. Like, we literally had the same outfit on," Liv Tyler recounted. "We had both had perms, like spiral perms, braces, pink frosty lipstick. We were both wearing an Aerosmith concert T-shirt with black leggings and Reebok high top sneakers."