Billie Lourd Says She Teased Her Mom for Not Wearing a Bra — But Now Doesn't Wear One Either

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Billie Lourd is following in her late mother Carrie Fisher's style footsteps, even if she never expected she would.

The 29-year-old actress opened up to PEOPLE about Fisher at the Mujen Summer Kickoff Party in Los Angeles on Wednesday evening, admitting that she's now doing the thing her mom did that she swore she never would: walk around without a bra.

"I used to get mad at my mom for not wearing a bra. And now I sometimes don't have the energy to put on a bra," Lourd said.

"I'm thinking about my old self yelling at my mom about that and I'm like, 'Man, she was probably just tired and didn't feel like putting on a bra! Why was I hating on her for it!?'" the actress added.

If Lourd isn't getting as much rest these days it could have to do with the fact that the American Horror Story star is a new mom, to 20-month-old son Kingston Fisher (whom she shares with husband Austen Rydell).

"It's exhausting being a mom," she said. "Sometimes you can't even put on a sock. I go full robe most days. The fact that I have a dress on right now is a rarity."

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Lourd was all dressed up to celebrate Mujen, the rice-distilled craft-spirit brand founded by her stepfather Bruce Bozzi and his good friend, Sondra Baker.

Bozzi — who married Fisher's ex Bryan Lourd in 2016 — has been in Billie's life since she was 14, and told PEOPLE at the event that watching her prepared him to become a father himself.

"I learned a lot from Billie," said Bozzi of parenting his daughter Ava, who is about to go into high school next year. "[She] taught me a lot about being a parent and a lot about being a father to a girl, which is very specific."

Ava and Billie are close, the actress shared. "She steals all my clothes," teased Billie. "Every day I'm like 'I like that shirt' and she's like 'It's yours. It's from your closet.' "

RELATED: Billie Lourd Sings Fleetwood Mac in Emotional Tribute to Mom Carrie Fisher: 'We Loved This Song'

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As for Billie's own life as a parent, she said Kingston is keeping her busy. "He just does not stop talking," Billie confessed. "He is so smart and so aware. And he climbs everything. It's a little bit terrifying. It's highly terrifying."

Being a mom is her "No. 1 thing," she told PEOPLE — something that's changed her approach to acting a bit.

"I love acting. Acting is my passion and I adore it and there's something about working hard and staying busy that I am addicted to," she said. "But I definitely work to live, not live to work. And now that I've become a mom, it's the most important thing in my life. He's the most important thing so I really take jobs that are going to allow me to be around him as much as possible."

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And while it's still way too early to think about Kingston following his mom's footsteps into acting, Billie — who began acting like her mother, before Fisher's death in 2016 — is all for it if he wants to.

"I hope he's a doctor, but he can do whatever he wants," Billie shared. "I mean, everybody hoped I was going to be a doctor and here we are."