“Men are dogs,” we've heard many women say.

It's most often a value judgment based less upon their inclinations to fetch and beg as it is to cheat in a relationship.

Although there has been some research that confirmed what we all instinctively knew to be true – that men are more likely to cheat than women – there has never been any data that told us why. Until now.

Everything else being equal, there were only ever two possibilities. The first is that women have more self-control than men. The other is that men, well, are dogs. That they experience stronger sexual urges than do women.

Guess which option the scientists proved correct?

"Overall, these studies suggest that men are more likely to give in to sexual temptations because they tend to have stronger sexual impulse strength than women do," says Natasha Tidwell, a doctoral student in the Department of Psychology at Texas A&M University, who authored the study.

The problem, Tildwell went on to say, stems from the fact that sexual urges have a longer running start, evolutionarily speaking, then self-control.

"When people exercise self-control in a given situation, this sex difference in behavior is greatly reduced. It makes sense that self-control, which has relatively recent evolutionary origins compared to sexual impulses, would work similarly -- and as effectively -- for both men and women," Tidwell said.

Seventy men and 148 women volunteers were rounded up and asked to recall and describe an attraction to an unavailable or incompatible member of the opposite sex. Next they answered survey questions designed to measure strength of sexual impulse, attempts to intentionally control the sexual impulse, and resultant behaviors.

Upon analysis of the data, the researchers noted that the sexes did not differ in in the extent to which they exerted self-control. Put another way, men's self-control is just as rock-solid as women's. They just don't exercise it as frequently.

“If men fail to use self-control, their sexual impulses can be quite strong. This is often the situation when cheating occurs," noted Paul Eastwick, assistant professor in the Department of Human Development and Family Sciences at The University of Texas at Austin, who co-authored the study.

The research has been published in in the Personality and Social Psychology Bulletin.