When I rode the bus to school in the early 1960's, I often saw boys grope girl's genitals, with either rejection or a smile as the response.  Those were incidents between boys and girls of about the same age.  At that time, my state of residence required that girls and boys be at least 14 to get married, although if you crossed the state line into Georgia (as many did) the girl could be as young as 12.  Mating is primitive among the human race as a whole, but in Western nations, the girl's consent most usually is required.  Unwanted groping is cause for big brother to beat the tar out of the groper boy, but a lifetime sentence as a sex offender is, (without aggravating considerations) extreme.  On the other hand, jerks start their careers early.  Some sort of reconditioning involving punishment and education ought to be preferable to six years imprisonment of a minor, followed by a lifetime of listing as a sex offender.  

Please note that I said "(barring) aggravating considerations.