It is biographical. It should address why you want to be a doctor, how you have tested your interest and provide evidence that you have the attributes that schools are looking for in students and that society needs in its physicians.
Now, if you took a convoluted route to medicine (is that an "oddity"?) such that you need to explain, beyond what is in the Experience section, you may need to weave that into the essay. What might come to mind would be leaving school for a period of time due to a catastrophic event (tornado, wildfire, etc), injury, illness or to raise a child. Maybe something unusual about your childhood such as being raised by an older sibling after the death of your parents (or raising your younger siblings under similar circumstances). Flunking out of school due to circumstances that changed so that you came back and finished strong. I think you can see where this is going.
Some things are not odd enough to warrant a mention such as taking physics and biology as a senior because you decided late to be premed.
