Most parents first experience their child's attempts at autonomy at about age two.
They feel challenged and often a battle of wills begins that lasts throughout childhood and the teen years. From about the age of two, and at differing intervals in the developmental process, children are individuating from their parents and the world around them. This includes making decisions for themselves, exerting their power and will on persons and situations, getting their own way, declaring ownership and authority. When parents react by overpowering children, they cause them to feel powerless. Since all humans strive to feel powerful, the overpowered child may react to his or her feelings of powerlessness by either fight or flight - either giving in and letting others make all the decisions and maintain all control or fighting to seek power through rebellious and destructive behaviors.