there's Rachel Aldana who at the age of 18 was the largest naturally busty woman in Britain, even bigger now due to pregnancy .
not- there are women who tend to get bustier even past there teen years base on genetics like Stepmeber Carrino, pregnancy also a factor.
there are also another naturally busty women like Hitomi Tanaka, September Carrino, Jana Defi , Merilyn Sakova and etc.