The only way to know if you'd be crap is to try writing. Short stories are a fun place to start, just pick a genre you like and give it a shot.
It's enough to simply read the right authors, or at least it was for me. You can tell if you belong in their company or not. If you can't, well... that's a strong hint in itself.
Find their first published stories. Find their earlier stories, sometimes they get used to fill out a shorts collection for laughs. Then ask yourself if you belong in that company.
And then ask yourself if you care, maybe you'll never write enough to have a shot at a publishing deal, much less a bestseller, but maybe you just like telling stories to yourself and maybe a few friends.
It's enough to simply read the right authors, or at least it was for me. You can tell if you belong in their company or not. If you can't, well... that's a strong hint in itself.