Im a person who grew up WAYY to fast. It should be called emotinol maturity as sometimes you can't control it. Inner age is like the age you feel like your supposed to be i think. Idk im a dumb person who saw too much on the internet XD. .
What's "Emotional Maturity" anyhow?
Is it the ability to control your anger (one should learn as a child), To motivate yourself, Improved frustration tolerance? How to accept that you will be dying shortly?
Or towards others - How to deal with romantic relationships, With business relations, With community, With the public?
There's so many aspects to this, And one keeps changing (and hopefully improving) right up to death.
"Age" implies there is a linear scale, Which could be expressed in numbers.
Before making such an implicit claim, Better make a good scale that can be validated to be applicable for the vast majority of humans.