"Everyone shouts at their kids"

You've seen it at the school gate and heard it through the wall. Every parent shouts. It's part of having children, and a book that treated it as a problem would be treating being human as a problem.

Murray Straus and Carolyn Field asked a nationally representative sample of nearly a thousand American parents about what they called psychological aggression, which covers shouting, yelling and screaming at a child, along with threatening and name-calling. By the time the child was two, nine in ten parents had done at least one of these in the past year. By five, nearly all of them had. The rates stayed in the nineties right through to seventeen. The researchers describe it as near universal. There were no real differences by family type, income or anything else. Severe forms were rarer, with about one parent in ten to one in five of toddlers' parents and about half of teenagers' parents reporting them in a year.

So yes. Everyone shouts. You're not unusual and you're not a monster, and if the shouting is once a month, in the way most people mean it, you might reasonably close this book. The question is frequency and heat, and that's where the research stops being reassuring.

Ming-Te Wang and Sarah Kenny followed nearly a thousand two-parent families with a thirteen-year-old. They measured what they called harsh verbal discipline, which is shouting, yelling, swearing at or insulting a child as a way of correcting them. Where mothers and fathers used it more at thirteen, their children showed more conduct problems and more symptoms of depression at fourteen. It ran the other way too. A child's misconduct at thirteen predicted more harsh discipline from the parents at fourteen. And parental warmth, which you'd hope would soften it, didn't. Children of warm parents who shouted at them fared no better than children of cold ones. Chapter 9 returns to that.

That study is about teenagers and about the harsh end, with swearing and insults in it. It doesn't say that raising your voice once a fortnight damages a child. What it suggests is that shouting as a routine tool of correction, at the level that the ladder produces when it's run several times a week, goes with children doing worse, and that the being-worse feeds more shouting. That's the loop from chapter 3, measured over a year in a thousand homes.

So the fact that everyone does it tells you it's normal. It doesn't tell you it's free, and it doesn't tell you that the amount you're doing is the amount that everyone means.