My family has started to wade in the waters of sex education. I've read that it's smart to talk, and talk, about sex, so that kids do not begin to conclude that certain natural behaviors are filthy and worthy of shame. For example, I'm told, a two-year-old should start to get familiar with the terms "vulva," "vagina," penis," "clitoris," "bum," and "nipples." These should just be parts, like any other parts, like your head, shoulders, knees, and toes. To demystify the word "penis," and to convey the sense that the world is wide, you could mention to your child: "Not everyone with a penis is a boy." I said this, and my husband choked on his coffee; "I just, I thought you might begin with some context," he whispered. Then: "I guess I have to learn not to giggle when I hear the word penis ." I am not a barricade-building revolutionary, but some tired ideas about gender really bothe...