@maxdancona,
I agree that today's 21 year olds, male or female, are a far cry from 21 year olds of the past, but all of science disagrees with you. From birth, females mature faster and reach maturity quicker. It takes longer for the male of the species to mature, not only in body, males grow until 21 while females are fully grown by 14 on average, but also mentally.
It's the way the animal evolved. Your experience is at odds with it, but it obvious that you have probably treated many adolescents in your medical practice and raised several children. So, I will let your vast and worldly experience supersede that of the medical community.
Thank you for teaching us all something. You should really bring this up at the next AMA as the medical community believes the exact opposite.