I think it makes a difference, but only if you can tell it's the real person. For example, I see a lot of people all over the Internet who use a stock photo for their avatar and I think it's to give off a "professional" feel.
However, I don't really feel that it's really all that professional to use a picture of a person that's obviously not yourself as your avatar photo.
Stock photos are known for being "fake" and HubPages strongly urges users to use their own pictures in their hubs, especially ones that are taken with a semi-decent camera, with good lighting, etc.
It's because people can smell "fake" from a mile away. When using a fake photo for an avatar, it's the same thing. People want to read content from people who speak from the heart and from their own experiences. I think having a realistic photo of yourself can help convey this image.
It's not just a female thing, it works for men, too. Even people who don't consider themselves attractive can pull it off. Just put on a decent shirt, go outside or somewhere where there is good lighting and work on getting a great avatar photo!
To answer your question, I think a REAL photo of yourself taken in good lighting really affects your followers AND your readership as a whole. I think it increases how believable your content is. It makes people think you've really been there -- actually have done the things you speak of in your hubs.