MERCED, Calif. -- There are gateway drugs.
And then there's gateway sex.
Researchers have found that half of teens who have oral sex during the ninth grade will engage in intercourse by the end of the 11th grade.
They also found that most sexually active teenagers will begin oral sex and sexual intercourse within the same six-month period.
Those are the results of a new survey conducted by researchers at the University of California-Merced and the University of California-San Francisco.