I see a new study says that most Americans think someone is grownup when they reach 26. Personally, I think people are grownup when they stop growing up vertically, which is about 18. The real question is: when does someone become an adult? The sad truth is that, in my life, I have met only one or two people who qualify as adults. All the rest are children in grownup bodies. What would your criteria be?
yours, Peter T.