The talk show host Tyra Banks declared a teen sex crisis last fall after her show surveyed girls about sexual behavior. A few years ago, Oprah Winfrey warned parents of a teenage oral-sex epidemic.

We all know that teenage are having sex all the time,right? Turns out we are wrong.

The news is troubling, but it’s also misleading. While some young people are clearly engaging in risky sexual behavior, a vast majority are not. The reality is that in many ways, today’s teenagers are more conservative about sex than previous generations.

Today, fewer than half of all high school students have had sex: 47.8 percent as of 2007, according to the National Youth Risk Behavior Survey, down from 54.1 percent in 1991.

A less recent report suggests that teenagers are also waiting longer to have sex than they did in the past. A 2002 report from the Department of Health and Human Services found that 30 percent of 15- to 17-year-old girls had experienced sex, down from 38 percent in 1995. During the same period, the percentage of sexually experienced boys in that age group dropped to 31 percent from 43 percent.