LONDON — Last week, Taylor Swift won her symbolic $1 case against a former radio D.J., David Mueller, who assaulted her by groping her bottom under her skirt at a preconcert photo session in 2013. When Ms. Swift’s mother, Andrea Swift, took the stand during the trial, she testified that her daughter had agonized over the fact that she had said an almost automatic “thank you” to Mr. Mueller and his girlfriend after the photo shoot.

“She couldn’t believe that after he grabbed her, that she thanked them for being there,” Andrea Swift said. “It was just destroying her that she said that.” Breaking down in tears, she went on to say, “As a parent, I questioned why I taught her to be so polite.”

Neither she nor her daughter bears any responsibility whatsoever for the assault, as Ms. Swift powerfully pointed out in court. But Andrea Swift put her finger on an important truth. We raise girls to be pretty, pliant and polite. We raise boys to be loud, demanding and confident.

It starts from babyhood, with onesies featuring pretty princesses and future presidents. We “shush” little girls, contain and silence them, while boisterous boys are expected to make noise. We train girls to practice far more self-regulation than their male peers. Research shows that parents interrupt girls more often than boys and that boys are more likely to speak up in the classroom.