Myriad psychological, cultural and economic variables play a role in the frequency and expression of infidelity. But one thing is clear: infidelity is a worldwide phenomenon that occurs with remarkable regularity, despite near universal disapproval of this behavior.
Read more:
http://ideas.ted.com/2014/01/23/10-facts-about-infidelity-helen-fisher/
The article has an excellent reading list also!
Amanda