To the many insightful comments in this thread, I'll add two more thoughts:
1) When it comes to aspiring writers, as opposed to the general population, there's a powerful pre-selection bias at work. If you love stories, if you dream of stories and long to write them and can't manage to stop inventing them even when you ought to be doing something else... Well, that's probably because you're one of the people who already has innate talent.
2) 'Innate talent' is not the same thing as 'easy learning curve'. If
Felix Klieser can learn to play the French horn without arms, then a talented aspiring author can learn to create awesome fiction despite severe grammatical handicaps. It's a matter of recognizing one's limitations and working around them.
...which is all just my way of saying that if you want to write fiction, do it! Don't worry about whether you fall into the 'talented' category or not. Or at least, not until you've spent a few years learning your craft.