The Real Housewives of Beverly Hills star, 56, made the shocking reveal after calling her longtime friend Denise Richards a "hypocrite" for getting upset when the group talked about threesomes within earshot of Richards' teen daughters and their friends at a dinner party.
On the most recent episode of the Bravo reality show, the subject came up during a cast trip to Santa Barbara when Rinna asked Richards if her daughters had seen her movie Wild Things. The racy 1998 film featured a scene in which Richards' character was involved in a threesome.
"I hope to God they haven't seen it," Richards said of her daughters.
But Rinna admitted that her own daughters, Delilah Belle and Amelia Gray Hamlin, have read her 2012 book, The Big Fun Sexy Sex Book, and that they even picked up some oral sex techniques from it. Rinna revealed that her daughter told her she read her sex book when she was just 11 years old and added that she'd rather her daughters learn from her than on the streets.
"At least I taught them how to do it right!" the mom of two said.On social media, some Real Housewives of Beverly Hills fans blasted Rinna for boasting about her book. Others called her out for putting Richards on the spot regarding past grownup talk that didn't involve the children, and for comparing her book to a sex scene that she filmed years before her daughters were born.
"Lisa Rinna's logic/ justification on how she's ok that her 11yo's read her book…. because she taught them how to do it the right way is mind boggling," one viewer wrote on Twitter.
"You're a terrible friend," another user tweeted to Rinna. "To do that to Denise, your friend of 20 yrs?! …Just because you talk (they read your book) to your kids about sex, doesn't mean Denise has to parent the same way."
"[Lisa Rinna] needs to slow her roll," another person tweeted. "be a gd friend to Denise and show you understand the difference between talking to adults and children. your kids may have read your book but you and your friends didn't buy it for them and do a read-aloud."
Rinna's daughters were aged 13 and 10 when she wrote her sex book. In an interview with CNN at the time, the future Real Housewives of Beverly Hills star said her daughter Delilah called the book "awkward" when she first found out about it.
Rinna also explained that she hoped her daughters would be able to use the book as a guide to having a healthy sex life as young adults as opposed to waiting until their mid-30s to "try and figure it out."