Hmmm... I bet you could do it just fine! Sounds like you're talking yourself out of it instead of into it :) I do that all the time....
But seriously, judging by the biographies on shelves these days, you don't NEED training/experience/talent at writing them. So the fact that you're a good researcher (judging by your blog) and a talented writer should place you well ahead of the game.
I'm using my marathon-finish-line icon to emphasize my point *grin*