User blog comment:FairyRaven/Fairy Tail Chapter 421: Wendy and Chelia, Review and Commentary/@comment-24360548-20150224232958/@comment-5668006-20150225145330

Well not to disagree for the sake of disagreeing nick but it depends on 1 that human and 2 that humans age whether or not they change a lot in a year. Also, it's a huge fallacy to say humans cannot change much in a year because that statement accounts for mental/attitude changes which in a year, yes any human on earth can change drastically mentally depending on the year they had.

For example, on the first two points, a 12 year old turning 13 is a huge deal physically and mentally because that is the typical age of puberty - say Wendy for example who 100% should be taller. It's obvious she has matured mentally as well. Also, if Natsu has been "training" for a year he should physically be larger, regardless if he is training his heat and fire magic - there had to be strenuous physical training involved. Either way, idk why I decided to write this since it will never be a big deal either way. - I am disappointed Mash changed Wendy and Natsu's hair back to normal though, super lame.