well 14.5 year olds sexual development can not be differentiated from 18 year olds, but I have heard that 15 is where mental development reaches the point where there is not as much 'yielding to elders', so from a physical attraction point of view anyone who says 18 but not 14.5 is a liar, but 15 seems to be the best overall age to allow consent, if you take both participants perspectives into consideration (which of course you should).