I just say say only ... Haha!Woah, jal you r one garang woman....fierce huh!
This is what i know, for a person to behave in a particular way/s. Genetics alone is not solely responsible for it. It has to be a combination with environmental factors (for a case like affair) Pull environmental factors eg: more sayang and pamper frm potential 3rd party, job-related matter like more travelling, strong memories over past love life, etc. Push environmental factors eg: pressure at home, spouse has lost the attractiveness or zest, he/she pays lesser attention to the other.
In a way, we sort of have a control over our environmental factors . So, dont't worry too much over the genetic cause yah....perhaps play a more active role in deterring bad environmental influences that can shake one's relationship.