is, "How old is this artist?"

I'm sorry but it's true.  Art Collectors like to know the age of an artist.

Please, please, please get past the vanity and simply include the year you were born on your biography. 

It's an essential piece of information when marketing art.

No one is judging you and it's a plus either way:  If you a teenager or twenty-something, people will be excited to discover someone "up and coming" and if you're.....more seasoned, people will respect your experience and maturity (of course, these are snap judgements that could be wrong in either case, but that's a different story).

But there's no denying the fact that collectors want to know your age, so you might as well stop complaining about it and embrace the fact that you are an artist!  And that's a good thing at any age.