It is estimated that car insurance for teenage boys is high because the rate of accident is nearly as high as 90 percent. In other words, it is highly likely that boys will be involved in some type of accident during their first years of driving. Girls have lower rates, but this too can still be considerably more than those rates for boys.
Also keep in mind that differences in the cost of the insurance will be in the type of car driven. The combination of a sports car and a teen boy will cost you significantly more than other vehicles, since these cars are often driven over the speed limit and therefore are a higher risk.