The age at which the law imposes adult legal responsibility
The age (set by state law) is when a parent is no longer legally responsible for their child. In many states, the age at which the law recognizes the child as an adult is 18, while in other states, it’s 20 years old.
Turning the age of majority implies that one has more control over their behavior and can be a self-directing adult, even though most children grow up and mature at different stages in their life. The adage, “…He should have known better…” might be true, except that no two children (or adults) have identical experiences in life. Some children mature early. Others need more time to adjust and mature.
Once the child becomes a legal adult – the age of majority, the parents are no longer legally responsible for their child’s actions or welfare.