Why do men cheat? This question is splashed across magazine covers every time there's a fresh high-profile cheating scandal.
The answer is there's no one answer, according to Helen Fisher, a biological anthropologist at Rutgers University.
Fisher divides the brain into three systems: the sex drive, the desire for romantic love and attachment. Because these systems don't necessarily need to work together, "the brain is, alas, built to enable us to love more than one person at a time," Fisher explains.
Biology, however, doesn't excuse behavior. Humans also have the mental capacity to make decisions not based on impulse.
However, because we all have a different biological map, according to Fisher, some are more susceptible to cheating behavior than others.