http://www.nbcsandiego.com/health/5058432/detail.html

SAN DIEGO -- A new study shows that teenage girls are having sex at a younger age than ever before and are taking the lead in dismantling sexual taboos.

According to the study, the percentage of young girls who participate in premarital sex jumped from 12 to 79 percent over the last 60 years, while the percentage of young men who participate in premarital sex jumped from 42 to 71 percent.

The study, which was co-authored by Jean Twenge of San Diego State Univeristy, looked at sex surveys done between 1943 and 1999. It found that the average age teenage girls had sexual intercourse in 1999 was 15. The average age during the 1950s and 1960s was 19. Overall, the percentage of sexually-actively teenage girls in 1999 was 50 percent, compared to 13 percent in 1943.

Twenge said birth control and cultural acceptance are the main reasons for the changes. She does not feel the prevalence of sex on television has contributed as much to the phenomenon as people think.

"Television shows like Dawson's Creek and The OC that show high school sex didn't really show that until it was actually happening in high school," Twenge said. "It was really art imitating life instead of life imitating art."

The study also showed that oral sex is not nearly as taboo today as it was in previous generations. Between 1969 and 1993, the rate of women engaging in oral sex climbed from 42 percent to 71 percent. For men, the rate grew from 48 percent to 72 percent.

"In previous generations, oral sex was considered disgusting," Twenge said. "Now young people see it as another way of being sexual. It's also part of the general trend of sexual behavior moving away from marriage and reproduction and toward pleasure."

The study appears in the latest issue of the Review of General Psychology.