I've been drawing since I was about 4-5, just doodling here and there on my books and notes and desk. I wasn't fantastic but I loved it.
Then all of a sudden I instantly switched to drawing realistically. Over a matter of hours I changed from doodling cartoonish figures to accurate detailed drawings. Or at least accurate for back then.
It surprised me at first. But soon I realized being able to draw something realistically isn't a matter of years of study and practice but a way of thinking or seeing something.