If you are able 

To Write a Book

- You're surely able

To Write Some Bio

Too!  ^_~ 

And if you don't 

Want to 

You don't have to

Tell your age there

- But please tell

Your readers at least

If you're a Boy 

Or a Girl !

If they can't guess it 

from your profile pic

Or username

( Unless you are 

An RP Character! 😉 )