At which point?

Elizabeth

So, just started thinking and decided to make my first CC post. I read two different posts today. Both had to do with 18 year olds. On one post many people said the individual was 18 and an adult and could make their own decisions. That the parent really could not say much about what was going on due to the girl being 18. The second post people said that the boy was only 18, still basically a child, and still needed parenting and was not at fault. So my question when do you decide if an 18 year old is an adult or still a child? (I know legally speaking they are adults)How do you make that call? I hope this is controversial enough for the page.