Age doesn't arbitrarily determine your maturity and readiness for sexual relations. Mnay, many 18-20 years old are no more ready for sex than a 13 year old (mentally anyway). On the flipside, many 14-16 year olds are mature enough to understand the whole thing, and act responsibly.
Age alone is not enough for me to judge the appropriateness of a relationship. I mean, if its a use/abuse relationship, than its not right, no matter how old you are. But if its what might be thought of as "love", and the relathionship is a genuine one based on shared values, intimacy and understanding, then I see no reason why a 15 year old should not be able to date a 30 year old.
Its a culture stigma, which has no real logical explaination. Its like when one black guy calls another black guy nigger, and thats OK. But its not OK for anyone else to do it. The difference in age is not the sole measure of the worthiness of a relationship.
Needless to say, this only goes up to a certain point. If a 40 year old goes after a 10 year old, I say society has every right to **** him up. Its has to be determined on a case by case basis. However, I am all for shutting down kiddy pron websites and chatrooms. 16+ is OK,maybe 15, though its a sort of touchy subject. But anything less than 15 is out of the question, atleast online.