Crane spent half of his childhood in the humiliating care of his overprotective mother Yan Fan, who took extra precautions for his safety by keeping him inside their hazard-free home and putting him in a suit of armor, for she thought her son to be too frail to take care of himself. When he started sneaking out of the house, however, the young crane joined a Kung Fu class that he was amazed by, but it was too advanced for him that he kept getting injured during each session. By the time his mother found out, the sight of what he got himself into gave her heart pains and a hatred of Kung Fu, thus making Crane promise not to practice the martial art again.
Kung Fu Panda: Secrets of the Furious Five
Kung Fu Panda Holiday
in Crane on a Wire it is revealed he's allergic to silk