When Molly was in fourth grade, I would go to her school once a week to have lunch with her. The friend she often chose to sit with us at the parent table—her best friend at the time—would often ask me the same question.
“Are Lilly and Molly sisters?”
Patiently I would explain that my daughters were born at different times and in different places in China, but they are sisters now. My words seemed to satisfy her, at least until the next time I came for lunch.