Here's my theory. First, let's look at what kind of teenagers are having sex. Apparently, it's the dumb ones.
High-school age adolescents with higher IQs and extremely low IQs were less likely to have had first intercourse than those with average to below average intelligence.After reading this, the natural tendency is to say that a better education for kids might reduce their chances of indulging in high-risk behavior, in this case sex. However, that idea supposes that IQ is something which can be elevated with education, and almost all the research tells us that IQ is mostly inherited.
In fact, a more detailed study from 2000 is devoted strictly to this topic, and finds the same thing: Smart Teens Don't Have Sex (or Kiss Much Either).
The team looked at 1000s of representative teens grades 7-12 in the National Longitudinal Study of Adolescent Health and The Biosocial Factors in Adolescent Development datasets, both of which include an IQ test, and include detailed sexual experience questions ranging from hand-holding to intercourse. As with the other study there was a curvilinear relationship: students with IQs above 100 and below 70 were significantly less likely to have had intercourse than those in between. Also like the other study, they found teens with IQs ranging from 75 to 90 had the lowest probability of virginity (the authors note this is also the same IQ range where propensity towards crime peaks). Read the article here.
For instance, according to this entry,
The role of genes and environment (nature and nurture) in determining IQ is reviewed in Plomin et al. (2001, 2003). Until recently heritability was mostly studied in children. Various studies find the heritability of IQ between 0.4 and 0.8 in the United States;that is, depending on the study, a little less than half to substantially more than half of the variation in IQ among the children studied was due to variation in their genes. The remainder was thus due to environmental variation and measurement error. A heritability in the range of 0.4 to 0.8 implies that IQ is "substantially" heritable.So what that means, essentially, is that unintelligent people are mostly born that way, and education can help them but little when it comes to IQ. These "genetically challenged" teens are more likely to have sex earlier, thus putting them at greater risk of getting pregnant, and thus putting us as a society at greater risk of having even more "genetically challenged" parents in the future. In sum, stupid people have more babies, which, of course, explains the popularity of "Dancing With The Stars" and "300".