The issue of when you are an adult is a trickier question than you might imagine. I have written in a previous answer about how children in North America would leave home around 13 or 14. There would be transitional spaces such as rooming houses or boarding houses before they were fully Independent, but they were fully functional “adults” by 15 or 16.

You can see this in the coming of age rituals for various cultures. The bar/bat mitzvah at age 13, the quinceanera at 15, the sweet sixteen for white folks. I do note that many of these are female centered and signal availability for dating/marriage. Boys just became men without much ceremony.

We still have a gradual introduction of rights and privileges with age. In my jurisdiction courts will consider a child’s wishes in divorce starting at age eight. You can be charged with a crime at age 12, you can work for wages at 14, you can drive at 16, vote at 18. Alcohol consumption is 19 where I live but is 18 in many parts of the country.

So why 18? It matches up with other markers of maturation like graduation from high school. Could it be 17? Probably. Should it be 16? Possibly. But 18 used to be an age of independence. You could expect to be leaving home and starting a life separate from your parents. That has certainly changed. If we were to keep things in alignment maybe we should push the age back into the mid-20s? 😆