Is your theme gravatar-enabled? If it is, you’ll see a small image in each comment.
Gravatars are images that represent your online presence anywhere on the internet. Gravatar stands for Globally Recognized Avatars.
To find your personal avatar, you can draw your own or find some here or here. Then go to gravatar.com and upload your image to match your email address. Anywhere on the internet that you sign in using your email address, will now be able to view your gravatar. It will display on those sites only if they are gravatar-enabled. Is yours?