'Welcome to Plathville': Barry Plath Suggests Olivia Is 'Brainwashing' His Son Ethan (Exclusive)

In PEOPLE's exclusive sneak peek at the season 5 premiere, Moriah and Micah share their concerns about their brother Ethan's wife, Olivia, with parents Kim and Barry

There's no shortage of drama brewing in the Plath family.

In PEOPLE's exclusive sneak peek at Tuesday's season 5 premiere of TLC's hit series Welcome to Plathville, Micah and Moriah Plath vent to their parents Kim, 50, and Barry, 55, about their brother Ethan's wife, Olivia.

"Honestly, she's always hated the way we grew up," Micah, 22, says of his sister-in-law. "She's always talked crap. And Ethan has, I really feel like he's absorbed all of that."

Barry responds, "You know what it’s called? It’s called brainwashing."

Related: 'Welcome to Plathville' : Olivia Reveals Tensions with Mother-in-Law over Their 'Different Values'

In an interview, Moriah, 21, notes that things have seemingly gotten "worse" with Olivia, 25. The two were previously best friends, but appear to no longer be on speaking terms. The tension between them has only increased as Moriah has grown closer with her parents again.

"Olivia has said a bunch of things about my parents for years, and it's only gotten worse," she says in a confessional. "It's gotten to the point where lies are being told. And I personally want to do my part in making things right."

Related: Welcome to Plathville's Olivia Opens Up About Moving Away from Ethan's Parents, Starting a Family

Moriah brings up the "credit card story" as an example, referring to Olivia's allegation that Kim stole money from Ethan. "The way I see that is, she was using, basically, a made-up story to validate her big emotions," she says.

She adds that she understands and accepts how Olivia feels about her family, but she simply refuses to tolerate her "lies" any longer.

Related: Olivia Plath Says She's 'Happy' and 'at Peace' amid Rumors She and Ethan Have Split

"That makes me so mad, because I sat there by her side for years saying, 'You are valid. You can feel however you want to feel,'" she shares. "But I will not tolerate lies being told. I will not tolerate somebody just then going off the deep end."

"You have every right not to like a person that's okay. And you have every right to be like, 'Their values or their beliefs or whatever, don't line up with mine and I don't want to associate with that,'" she continues. "That's okay. But it's not okay to try and make the whole world or a whole family feel the same way."

Barry agrees with his daughter's assessment and calls Olivia's behavior "relationally destructive."

"I see that now," Moriah says. "And that's why I choose not to have a relationship with her anymore."

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Welcome to Plathville season 5 premieres on Tuesday, Sept. 5 at 10 p.m. ET on TLC.

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