Boston child development expert Joani Geltman tells us that when she suggested that her daughter, actress Ari Graynor, write the foreword to her new parenting book, her publisher was skeptical. “Usually you get a famous expert to write the forward,” Geltman explained. But in many ways, Graynor, a Buckingham Browne & Nichols grad, was the best expert. At the very least, she could vouch for her mom. “Once they read it, they were totally on board,” Geltman said. Graynor, who stars in the new CBS comedy “Bad Teacher” (based on the 2011 movie starring Cameron Diaz), writes in the introduction to “A Survival Guide to Parenting Teens: Talking to Your Kids About Sexting, Drinking, Drugs, and Other Things That Freak You Out” that her mom is her “survival guide.” Graynor also makes it clear that the book “is not about how [Geltman] parented me (thank God). Her life’s work has been to understand human beings and to help guide them.” Geltman said she’ll be surrounded by family at her Porter Square Books reading Monday night.