A difference between an addict and a recovering addict is that one hides his behavior, while the other can’t stop talking about it. Self-revelation is an important part of recovery, but it can lead to awkward moments when you meet a person who identifies as a sex addict. For instance, within a half-hour of my first meeting Neil Melinkovich, a 59-year-old life coach, sometime writer and former model who has been in Sex Addicts Anonymous for more than 20 years, he told me about the time in 1987 that he made a quick detour from picking up his girlfriend at the Los Angeles airport so he could purchase a service from a prostitute. Afterward, he noticed what he thought was red lipstick on himself. It turned out to be blood from the woman’s mouth. He washed in a gas-station bathroom, met his girlfriend at the airport and then, in the grip of his insatiability, had unprotected sex with her as soon as they got home in the same bed he said he had used to entertain three other women in the days before. Is this a man with colossally bad judgment or one with a blameless addictive disorder? In the past year, this question has presented itself with dependable regularity. Most famously, Tiger Woods received sex-addiction treatment last winter after he admitted to infidelities; at least a dozen women came forward to claim they’d had sex with him. The chronically undisciplined Charlie Sheen recently sought help in controlling a variety of runaway appetites, including a fondness for the company of porn actresses. Earlier this month, Republican Congressmen Christopher Lee resigned after he was caught e-mailing a shirtless photo of himself to entice a woman he met on Craigslist. And then there is Silvio Berlusconi, the uninhibited Prime Minister of Italy, where prosecutors want him to face trial for accusations that he paid an underage girl to have sex with him. Berlusconi has never hidden his partiality to beautiful women, but he has called the allegations and reports of louche parties at his villa politically motivated. All these cases differ in scope, but a central question remains: Why would these men risk everything to satisfy their urges? When it comes to addiction, the line between morality and disease has always been blurry. But only in the past 25 years have we come to regard excesses in necessary cravings hunger for food, lust for sex as possible disease states. In 1983, when Melinkovich was continuously cheating on his then wife , a Minnesota-based addiction-treatment organization called the Hazelden Foundation published a foundational book called Out of the Shadows: Understanding Sexual Addiction. The book, which is still in publication, helped create the field of sex-addiction treatment. Its author, Patrick Carnes, is now executive director of Gentle Path, the sex-addict program Woods is said to have entered last year in Hattiesburg, Miss. The American Psychiatric Association is debating whether sex addiction should be added to its Diagnostic and Statistical Manual of Mental Disorders. The addition of what the APA is calling “hypersexual disorder” would legitimize sex addiction in a way that was unthinkable just a few years ago, when Bill Clinton’s philandering was regarded as a moral failing or a joke but not, in the main, as an illness. APA recognition of sex addiction would create huge revenue streams in the mental-health business. Some wives who know their husbands are porn enthusiasts would force them into treatment. Some husbands who have serial affairs would start to think of themselves not as rakes but as patients. This is already happening. In the year since Woods made sex addiction famous, rehab facilities accustomed to dealing with alcoholics and drug addicts have found themselves swamped with requests for sex-addiction treatment. The privately held company Elements Behavioral Health, which operates high-priced rehab centers around the U.S. including a celebrity-friendly one on a breathtaking mountainside in Malibu, Calif. recently acquired the Sexual Recovery Institute, a Los Angeles center for sex addicts. The institute’s revenues grew 50% in 2010. But the legitimacy now being granted to sex addiction requires a closer look. In the 20th century, we changed our thinking about alcoholism: what was once a moral weakness came to be understood as an illness resulting in large part from genetics. Sexual acting out seems different, though. Is excessive lust really just another biochemical accident? See more about what happens in sex rehab.