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Cityfile has partnered with Dr. Helen Fisher to bring you the latest insight into love and romantic attraction. A renowned biological anthropologist, Dr. Fisher has conducted extensive research in the fields of human sexuality, love and marriage. She serves as Chief Scientific Advisor for the internet dating site Chemistry.com.

Question: What's the allure of bad boys, bad girls, and bad relationships?

Answer: The thrill. Novelty, excitement, unpredictability: thrills and anticipation juice the dopamine circuits in the brain and you feel good.

Very good.

Dopamine is the chemical that soars when you take cocaine, anticipate winning money, or reach for a chocolate bar—and bad boys and bad girls can give you the dopamine "rush" of your dreams. Then they disappoint you and these reward circuits crank into overtime as you focus harder on your goal. And when you do win, you only want more. Given the opportunity, laboratory rats will push a lever hundreds of times to get a tiny amount of cocaine. Eventually many drop dead of emaciation and exhaustion. Instead, eventually most humans walk, never forgetting the one that got away.

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The good news is that even bad boys and bad girls will eventually have the tables turned on them. Someone will come along who knocks their reward system into overdrive; they'll fall madly in love, and they, too, will be ignored or dumped and feel the same despair of frustration and abandonment. If you play the game at all, at some point Lady Love takes her toll.

Visit Chemistry.com today to complete your free personality test and get your first chemistry inspired matches FREE!