> Ask any 22-year-old woman if she is the same person emotionally/intellectually as when she was 16. How many would say yes? Not many.
Ask any 35 year old the same question. You'll get the same answer. There is no bright line where people are mature.
You never stop maturing, not at 40, not at 75 either.
You just have to pick a number, but don't pretend there is any scientific basis to it.