Whilst that may be silly by today's standards and jailable, biologically speaking, it is not abnormal. The greater the age gap the bigger the issue is imho. For example, if a 17 year old was with a 15 year old, he would be almost vilified as a paedophile in Britain, which I think would be stupid. In Sweden the age of consent is 15, in Britain it is 16. I think 16 is probably the best age if we want to be legal about it, but morally this question is not so clear cut.
The age difference is far more important to me when talking about 14,15,16 year olds than any man-made law. Of course, it all depends on circumstance. A 20 year old who was taking advantage of a 14 year old (maybe with learning difficulties) is a whole different comparison. And 20 with 14 is quite a large gap if we are honest. Nethertheless, by today's law you are risking jail and being very silly.
What is the age of consent in America? 18?