If you’re a mom or dad and you learn that your child is sexting, that’s bound to set off alarms. But a new study reveals that the practice is quite common among teenagers, most of whom who think it’s no big deal. And that sets up an interesting dynamic in terms of how parents should handle the situation.

Researchers from Drexel University surveyed college students, asking them if they had ever sent or received “sexually explicit text messages or images” when they were under age 18. Fifty-four percent said yes—almost all of it in the context of a romantic relationship or as a means of flirting.

“We were shocked by the prevalence and the frequency of sexting among minors,” says David DeMatteo, an associate professor of psychology and law at Drexel and one of the study’s authors. He notes that previous studies have indicated the pervasiveness of sexting was much…