Many tedious circles can be gone round during discussions within this domain, so I tend to applaud those who want to focus more on the aspects of power, i.e. unequal power dynamics between people, and the opportunistic and systematic ways this stuff is exploited, rather than exactly what age people can be having sex at without it being 'unnatural'.
This is quite interesting, can you point me to a society that doesn't have 'power dynamics'? If not, the case for this being a naturally occurring event seems to hold more credence.