After reading about the 9 year old participating in a group rape (sorry no link atm, but i'm pretty sure there was a topic here) - i don't think our "age shemes" apply anymore - not telling that they're all rapists, but 10 years ago the youngest rapist was like 16-20, today the youngest rapists are < 12 - that's crazy and telling quite a story about the youths relationship to sex.
The 13 yo have more sexual experience today than 18yo had 10 years ago ... of course that's bad - but changing that will be quite a challenge (btw. i blame tubes
and parents not capable of protecting their child's computers ...)
Still don't get the point of your original post, a 13 yo guy fucked and dropped by a 16 yo girl would be equally bad as the 13 yo girl fucked and dropped by a 16 yo boy in my opinion ...