The physical differences between the median 23yo and the median 16yo, of both genders, being noticeably smaller than those between the median 16yo and the median 12yo...

(That is not to say that there can't be those exclusively attracted to adults, but frankly, I think that anyone attracted to under-25 or maybe even under-30, is probably attracted to a significant fraction of 16yo's of the same gender)

(That is also not to say that there aren't social differences between a 16 and a 23 that make dating each a different world (legality the first maybe, but I don't only mean legality, of course), so that they aren't possible to lump together in that sense, and I recognise it.)

(I wonder, though, if the differences between 16 and 23 could be compared, sociologically speaking, to other non-age-related social differences, such as social class, race or origin, religion, regional differences in countries, things like that... it would be a very interesting study)