Gwyneth Paltrow has revealed her "only regret" as a stepmother after marrying Brad Falchuk.
During the Sept. 26 episode of her podcast "Goop," Paltrow, 50, and Falchuk, 51, paired up for a discussion on second marriages, parenting and the future of their family.
The GOOP founder shares daughter Apple, 18, and son Moses, 16, with ex-husband and Coldplay rocker Chris Martin.
Two years after finalizing their divorce, Paltrow married television producer Falchuk in 2018 and became a stepmother to his teenage children, Isabella and Brody, whom he shares with ex-wife Suzanne Bukinik.
Paltrow confessed that she fumbled as a stepparent, at first.
"There's just no playbook for how to do it and nobody says, 'Hey, you're going to be a stepmother,'" she told Falchuk. "There's this archetypal evil stepmother and this inference that ... it's going to be this fraught thing."
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Paltrow acknowledged that her biggest regret in the role was her initial hesitancy to take it on fully. Then she described what she did to change it:
"Whenever it was, however many years ago, when I was just like, 'F--- it, these are my kids, I love them, I'm not going to be scared to discipline them or draw the boundary' — that's really what shifted everything."
Falchuk recalled an instance when Paltrow "yelled" at Brody, explaining the teen was "shocked," then relaxed, because he was being treated like "every other kid here."
Paltrow responded, "If someone asked me for advice on it, I would just say, 'From day one, really treat them as your kid. Meaning, don't have trepidation because ... you don't have jurisdiction.'"
"Be your full self as a parent with all the love and all the acceptance and all the boundaries," Paltrow continued. "I just wish I had done that earlier."
Related: 17 things I wish I knew before becoming a stepmom
Paltrow is right: Stepparents don't have a manuscript.
"It can take anywhere from one to two years for stepfamilies to adjust and for stepchildren to accept their stepparent in a new role," James Bray, a professor of psychology at the University of Texas at San Antonio, told TODAY Parents.
"If parents are too involved in discipline early on, children are likely to push back — even if stepparents have been in their lives long before marriage," Bray said. "With the legal title of 'stepparent,' the social and psychological impact changes (dynamics)."
Bray, the co-author of “Stepfamilies: Love, Marriage, and Parenting in the First Decade,” suggests stepparents hold back a bit in the beginning of the marriage.
Related: Gwyneth Paltrow shares rare pic with both children to close out the summer
"Focus on getting to know stepchildren with activities that help establish a positive relationship, and defer to biological parents for discipline," he said.
Pediatrician Dr. David L. Hill, the author of "Co-parenting Through Separation and Divorce: Putting Your Children First," agrees that stepparents should enforce rules set by birth parents.
"Couples need to have conversations about discipline before committing to a long-term relationship," he told TODAY Parents. "Otherwise, you'll come to a real impasse."
Those conversations will hopefully assuage biological parents who fear their parent-child relationship will corrode, said Hill.
"Stepparents can have a positive relationship with stepchildren," he added. "It just takes time to work."
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