I don't think it is stereotypically ANYTHING. Many writers start out with fan fiction - heck, two of the stories in Night Shift by Stephen King were fan fiction (one of Robert Bloch, primarily "Notebook Found in an Abandoned House") and the other, both stories part of the genesis of the arguably Dracula fan fiction novel (King does mirror a lot of beats in Stoker's novel), Salem's Lot, of H. P. Lovecraft (even down to mirroring HPL's style).
It may have become female dominated in the last few decades (especially with the success of 50 Shades of Gray which the author admits began as: "What if the characters in Twilight met as young adult professionals, and the 'vampire' gained power not through consuming blood but through S&M"), but in most cases it has been more the "training wheels" genre, the area where people who might be able to write start in - and some never leave it (whether they can write or not).