Delta FosB and Sexual Behavior
Behavioral addictions and drug addictions share common mechanisms and result is similar brain changes. This makes perfect sense as drugs can only amplify or decrease existing physiological mechanisms. The molecule Delta FosB appears to be the molecular switch for all addictions. It's a transcription factor, which means it turns genes on an off. Pseudoscientific arguments that behavioral addictions are qualitatively different or are "compulsions" rather than addictions have no basis in hard science. More studies on Delta FosB's role in addiction can be found here.