sqad; Also, the illegality or otherwise, depends on where you are, until recently the age of consent in Spain was 13 (now 16), but other European countries have different ages; Austria, Germany, Portugal and Italy it is 14, and in France, the Czech Republic, Denmark, and Greece it is 15.
When I was a teenager I could tell the difference between girls ages to a year, and I suppose the youths of today can do the same, but now I cannot tell the difference between a 14 and 20 year old (not that it matters!).