Though Jenna Bush Hager and Barbara Pierce Bush have lived their entire lives in the spotlight, they first became literary luminaries in 2017, with the publication of their bestselling joint memoir, Sisters First: Stories from Our Wild and Wonderful Life. Now, they’re attending BookExpo to show off their new picture book, also titled Sisters First (Little, Brown, Oct.), illus. by Ramona Kaulitzki. The twins will serve as cohosts at this morning’s Children’s Book & Author Breakfast.

They explain that their debut children’s book—about two inseparable sisters—had a protracted gestation period. “When Jenna and I first started talking about writing something together, we initially thought of doing a children’s book, but eventually we wrote a collection of personal essays for adult readers,” Barbara recalls. The idea of writing a picture book resurfaced during Jenna’s pregnancy with Poppy, her second daughter. “We had fun telling Mila, Jenna’s older daughter, how much we loved being sisters, and how lucky we’ve been to be partners in everything we’ve done—and Mila got very excited about having a sister, too.”

Not surprisingly, a lifetime spent hand-in-hand made for a smooth picture book collaboration. For inspiration, Barbara and Jenna relied on their own memories of their early sisterhood, as well as witnessing Mila and Poppy’s experiences. “The sweet relationship the sisters in our book have is so reflective of Barbara and my own sisterhood, knowing that we each have the other’s back all the time,” Jenna says. “But some of the text is based on actual things my girls have imagined and things they’ve said about each other. So, in some ways, the book really wrote itself.”

The sisters Bush are “deeply honored and excited to be among such incredible authors” on today’s breakfast podium, and they look forward to sharing their picture book with booksellers. “As we’ve grown older, our definition of ‘sisters’ has expanded to friends and colleagues—women who lift us up and help us believe that we are enough,” Barbara says. “Sisters First is a love story to them, too, as well as to the next generation of girls.” And, Jenna adds, “It is our wish for all women and girls—whether blood sisters or dear friends—that the power of sisterhood fills their lives with confidence and joy.”

Today, 8–9:30 a.m. Jenna Bush Hager and Barbara Pierce Bush will cohost the Children’s Book & Author Breakfast, on the Main Stage.