It must also be remembered that if the ancient father, as head of the family, held the permission of society to discipline wife and child even to severity of corporal punishment he was also charged with the task of insuring their obedience to whatever social laws were in force and was himself legally liable to punishment if he did not keep his family law-abiding.

That moral responsibility for the behavior of his family, early outlined in detail, was increasingly eased by the growth of personal relationship of women and youth to society.

That was shown in the laws that defined the extent of punishment allowed the father-head.

Although he might be secure in his legal right and duty to bestow on wife or apprentice "moderate castigation," an old Welsh law limited him to "three blows only with a broomstick on any part of the person except the head;" and another ancient law allowed the use only of "a stick no longer than the husband's arm and no thicker than his middle finger" in the case of the wife; while Blackstone's well-remembered restriction was to "a stick no bigger than his thumb." The moral responsibility of the father for his children, carrying with it as it did the liability of prison or even death for the misbehavior of sons, was governed by various statutes which show in the Middle Ages a growth toward freeing children from parental control and placing upon them when "of age" a definite and personal legal bond and penalty.
For example, we read that the Anglo-Saxon law held many children at the age of ten responsible for some acts which were forbidden, but that most youth were legally minors until the age of fifteen.

Until the early period of the eighteenth century it was still possible for a parent to legally sell his children, "a girl up to fourteen, a boy under seven." And after that period a wayward or troublesome son or daughter, or any of the offspring, when the parents could be proved financially incapable of their care, could be sent to convent or monastery.
The ability to bear arms seems to have been the criterion for legal coming of age.