How should I write this sentence better?
I would like to write

They both weren’t mature enough at twenty, an age that most people expects you to have matured up.

It seems odd to me how I expressed it. could anyone
show me how I can make it better?

Question

How should I write this sentence better?
I would like to write

They both weren’t mature enough at twenty, an age that most people expects you to have matured up.

It seems odd to me how I expressed it. could anyone 
show me how I can make it better?

Answer

Ohh, yes these are so much better.  I didn’t know “mature up” wasn’t a word, and I should really start using “neither” more.  Zak and Irene thanks a lot!

Answer

Hi Rou! Maybe something like:

Neither of them were that mature at twenty, an age when most people expect you to have grown up.

you can say: 
-to grow up
-to become mature 
 
but you can't say: 
to mature up

hope that helps :)

Answer

Neither of them were mature enough by the age of twenty.  By that age you are expected to have grown up.

Não perca a oportunidade de aprender uma língua no conforto da sua casa. Navegue pela nossa seleção de professores de línguas experientes e inscreva-se na sua primeira aula agora mesmo!