But....but....it's sourdough! You don't need yeast. You also don't need fanny juice to make your own starter! All you need is flour and water.
If you are lucky. The wrong yeasts and bacteria may be floating around in your kitchen. I get why one would ensure the right ones are there ...
But. Using yeast overgrowth seems counterintuitive. The woman who made yoghurt with vaginal lactobacili used the bacteria from a healthy vagina.
@Theoriginal: Sour, if the vagina is healthy. Fishy if the woman got PiVed recently and/or has an infection.
Could be used as a diagnosis method. 