1. The length of time that one has existed; duration of life:
2. The time of life when a person becomes qualified to assume certain civil and personal rights and responsibilities, usually at 18 or 21 years; legal age: under age; of age.
3. One of the stages of life: the age of adolescence;
4. The state of being old;
Do people act their own "age"? Or is it an "age" old question? In modern day society, we generalize ages and different actions. For example: A 6 year old most likely will not be able to understand sophistacted thought. They might be "immature" or "childish". A 20 year old will most likely be very mature and sophisticated. This person will be able to hold a conversation with you or be able to help you with homework.
But, one thing that we don't seem to recognize is that everyone ages differently. In adolescence, a boy might be growing facial hair while another has just had their first zit. Besides physical changes, there are very advanced mental changes. More ethics, more manners, more deep thought, anything. In my opinion, most people age according to their experiences. Someone that has had to rely on their parents might be less mature than someone who was raised to be independent.
Generalizing by age is wrong. Not everyone of the same age acts the same way. But, according to our government and laws, you must be 18 or older to buy a lottery ticket. Or 21 and older to buy or consume alcohol. Their reasoning is through science. That some parts of the brain are fully developed at these ages which allows for better reasoning. Yet, in other countries where there is no age limit, have less drug problems.
Age is a number, not something to speak for everyone.