WASHINGTON — "The O.C.," "Desperate Housewives" and other TV shows popular with teenagers generally have more sex than other programs, a study says.

TV executives say they're not pushing sex on children and that if parents don't want their kids to see certain shows then they have all the tools they need, including the "off" button.

According to the study released Wednesday by the Kaiser Family Foundation, the vast majority of TV shows — 70 percent — include some sexual content, with an average of five sex scenes per hour. On the top teen shows, the number is higher — 6.7 scenes an hour.

The study examined programming on ABC, CBS, NBC, Fox, WB, PBS, Lifetime, TNT, USA Network and HBO. Sexual content could be anything from discussions about sex to scenes involving intercourse.

The number of scenes involving sex has nearly doubled since 1998, the study said, from 1,930 to 3,783.

Examples of sexual content cited ranged from discussions of sex on the WB's "Gilmore Girls" and "Jack & Bobby" to depictions of oral sex on NBC's "Law and Order: Special Victims Unit" and sexual intercourse on Fox's "The O.C."

The study did not offer an opinion on whether sex on TV is harmful to children. But lead researcher Dale Kunkel said it's generally established that TV influences kids.

"Their sexual knowledge, attitudes, behaviors are all shaped in part by the characters in stories that television conveys," he said.

Kaiser released the study's findings at a news conference with Sen. Barack Obama, D-Ill., followed by a panel discussion with executives from NBC and Fox, Commissioner Kathleen Abernathy of the Federal Communications Commission and others.

Obama, the father of two young girls, said he shares the concern of many parents about what their kids are exposed to on television.

"We don't teach our children that healthy relationships involve drunken, naked parties in a hot tub with strangers — but that's what they see when they turn on 'The Real World,"' he said, citing a show on MTV.

"When they're fed a steady diet of these depictions over and over again from the time they're very young, this behavior becomes acceptable — even normal," he said.

Obama said the television industry needs to do more to help parents better navigate the ever-growing number of channels and programs. Making TV ratings easier to understand is one way, he said, adding that that if broadcasters and cable don't do more they are inviting Congress to act.

Tony Vinciquerra, president and chief executive of Fox Networks Group, said parents already have the controls they need on cable and satellite to block channels or programs they deem inappropriate.