Reaching the age of 18 is an important milestone for many people. It is the age an individual can vote, go to war and donate blood. However, there is the question of what age people truly become adults.  

While 18 is considered the age that a person legally becomes an adult, many people believe that at this age, one is not fully developed or mature enough to make responsible decisions. The human brain does not fully develop until age 25, and the prefrontal cortex – which helps control impulses, solve problems, regulate emotions and organize behavior – is only halfway developed by the time a person reaches the age of 18. 

In an interview with NPR news, neuroscientist Dr. Sandra Aamodt shared her professional opinion with interviewer Tony Cox.

“The changes that happen between 18 and 25 are a continuation of the process that starts around puberty, and 18 year olds are about halfway through the process. Their prefrontal cortex is not yet fully developed,” Aamodt said. “That’s that part of the brain that helps you to inhibit impulses and to plan and organize your behavior to reach a goal.”

Many cultures have coming-of-age ceremonies, like the bar mitzvah and the quinceañera, where one is considered to be an adult earlier than the age of 18.  At 21, many Americans are able to drink alcoholic beverages, buy cigarettes, buy tobacco and gamble. At 16, most teenagers can drive, and in some states, like Alaska, one can get married as young as fourteen with a guardian’s approval.  

AP World History teacher Kristen Owens shared her thoughts on what she believes makes a person an “adult.”

“18 is kind of a physical milestone, so it sort of levels the playing field in terms of who’s developed enough and emotionally prepared to make adult life decisions,” Owens said. 

While being mature is not the same thing as being an adult, maturity is still a big factor on what age a person becomes an adult. In order to live independently, a person would need to be able to make their own decisions and be able to support themselves. Every person matures at a different rate because there are many things that affect their age of maturity, like family structure and society constructs.  

Amelia Joyner (11) is in the AP Psychology class, where they have studied topics related to brain development and age of maturity. 

“I think independence is what makes us an adult. I believe that we’re adults when we can survive on our own and provide for ourselves. Of course, at 18 we’re legally adults, but some people reach an adult level of maturity before or after that age,” Joyner said. 

At 18 years old, many people are not ready to live on their own and are still relying on their parents for money and support. After college is usually when people start to live on their own and become independent.  

AP Psychology student Libby Cheek (10) has studied human behavior in class and thinks that independence plays a large role in what makes us adults.

“I think that we become adults when we are 18. I think that since that is the age you most likely would leave for college and start living on your own and using your own money, that makes you an adult. Once you no longer need support from your parents, you are an adult,” Cheek said.

While at 18 one could legally be considered an adult, often age is just a number.  Brain development, maturity levels and responsibility are also determining factors in adulthood.