Both men and women cheat — regardless of race, age or stature, according to Terri Orbuch, author of Finding Love Again: 6 Simple Steps to a New and Happy Relationship. In fact, about 32 percent of married men and 20 percent of married women report being unfaithful, she said.

But when powerful men — most recently CIA Director General David Petraeus — admit to infidelity, we’re often taken aback. (Or maybe some of us aren’t that shocked, after all.)

Petraeus joins a long line of philanderers in prominent positions: Anthony Weiner, Eliot Spitzer, Bill Clinton and John Edwards, just to name a few.

But regardless of whether you’re surprised to hear these men strayed, the question is the same: Why?

Why do powerful men with such pivotal professions and important responsibilities commit adultery? Why do men with so much to lose — great positions, families and reputations — risk it all for a fling?

Power certainly may play a role. For instance, in a survey of 1,561 professionals, Joris Lammers, an assistant professor at Tilburg University, and colleagues found that the more power people had, the more likely they were to cheat. Plus, the more power people had, the more confident they were.

(They also found no gender differences in past cheating or the desire to cheat. Women were just as likely to cheat or want to cheat as men were.)

Initial research also points to fascinating brain findings when people are given just a fleeting sense of power. Lammers told NPR, “You can see the brain structure associated with positive things, with rewards, is just much more activated than the part that is steered toward preventing the bad things from happening.”

The piece also talks about interesting research in college students, which found that when both male and female students were given a temporary sense of power, they tended to flirt more with a stranger of the opposite sex who sat next to them.

According to Orbuch, the sheer presence of temptation may explain why powerful men cheat. Power – and all that comes with it, such as wealth and fame – is attractive to many women, she said. And, sometimes, these women can become aggressive with their advances, she said.

Loneliness might be another reason. Men in power, including General Petraeus, are often away from their families for days, even weeks, Orbuch said. As a result, they end up yearning for female companionship, she said.

Some powerful men might crave the adrenaline rush. “They perform well under high stress and continually need and enjoy excitement or challenges to drive them forward. An affair gives them that same type of exhilaration in their private life,” Orbuch said.

These individuals also are surrounded by yes-men who placate them – and, often, their bad decisions. “Powerful men tend to be surrounded by people who protect them, idolize them, and even ‘enable’ their vices in order to remain inside their influential orbit.”

Having people in your inner circle who constantly approve of your actions can swell your ego. And it can make you feel like the limits you once put on yourself are loosening – and loosening, she said.

Powerful men might believe they’re impervious to getting caught or can conceal their transgressions because of the resources at their disposal, Orbuch said.

She also noted that powerful men – and people in general – cheat when they want change. “Something in the man’s life or his relationship isn’t OK, and the affair creates the trigger for change,” she said. That something might be boredom after many years together, she said.

Powerful men may cheat for a variety of reasons. But the result is usually the same: Positions, reputations and families are irrevocably broken.

Why do you think powerful men cheat?