Lady Bird begins with a Joan Didion quote splashed across the screen: “Anyone who talks about California hedonism has never spent Christmas in Sacramento.” Christmas is mostly for children or, at least, the child part of us. And, few come through childhood unscathed. Greta Gerwig’s charming, brilliantly written, funny, and psychologically real film has a lot to say about mothers and daughters. Being a mother has its challenges. Being a daughter means separating to have your own life. That has its difficulties too, especially when your mom has a hard time letting go. For Christine “Lady Bird” McPherson (Saoirise Ronan) and...