Maybe this was true awhile ago, but I would say that your guess would be not as sure a thing today. As a high-school student who attends parties and hears gossip, etc. (although I have kept myself chaste), I can vouch that in many, many cases, it is girls who encourage the guys to have sex. Just my $.02
Thanks for your insight, oakcon—you don’t want to know how many years it’s been since I was in high school!