Jessica Simpson explains why she's such an 'open book' with her children

"Open Book" isn't just the name of Jessica Simpson's memoir, it's also the parenting philosophy she practices with her children.

The fashion mogul, who is currently promoting the paperback version of her New York Times bestseller, told "Good Morning America" on Tuesday that her two oldest kids, 8-year-old daughter Maxwell and 7-year-old son Ace, both have it on their bedside tables.

With "Open Book," the 40-year-old said she set out to "rediscover" herself and felt she needed "to put this out into the world" so people could "understand me in a different way and on a different level and on a deeper level."

Despite diving into topics some parents might deem taboo -- such as her past relationships, addiction problems, weight-loss struggles, body image issues and sexual abuse -- Simpson said "there's nothing that's off limits" with her children.

"We're a very open family," she told "GMA."

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Simpson recalled signing autographs in New York City while promoting the book when it first debuted early last year with Maxwell by her side when a woman approached her. The woman, who also had her daughter with her, tearfully thanked her for being open about her experience with sexual abuse, saying it encouraged her to speak to her therapist and family about how her own experience.

"Maxwell was like, 'Mom, what is she talking about?' I guess this is the time that I'm going to talk to my daughter about it here in Times Square,'" she remembered. "But it was a perfect moment because she saw how being open and being honest with your feelings, how you can inspire people that way ... how it can make a change in people's lives."

The former reality star said her children know it's important to "have everything out there in the open."

"There's nothing that's embarrassing to talk about at all and there's nothing to be ashamed of and nobody is going to judge you," she said.

Simpson -- who has been married to Eric Johnson since 2014 -- also opened up about their daughter Birdie, who recently turned 2, calling the toddler "one of a kind."

The "I Wanna Love You Forever" singer said Birdie "makes all the farm animal noises" and "laughs at everybody's jokes."