From what I remember,unless Daneos changed it, you could not grow up without taking your master class. So, if he hasn't changed it, we should have master class.
thats a bit strange from what i remember (granted this was a long time ago like a month after the Taiwanese server) first came out but you could become adult w/o going into master class its just you receive the master class quest from korin who was right in front of you so you just naturally took it but i dont think you HAD to take it i can be completely wrong though.