Replying to https://twitter.com/undefined/status/1361626090750562306:

@daphneblake @vennmorwendian The NHS says that most people finish puberty around 14 years of age.

As to how fast people mature mentally and socially, it depends a lot on the place they grow up in. If your society constantly tells you you're a stupid immature irresponsible child, you'll probably be one.