As Freud said, it's all about mother.
Or, as modern day psychologists point out, fidelity begins at home. Whether a son grows up to be a philanderer, depends a lot on the models he has for parents.
Just this week, a British psychiatrist blamed nannies for creating unfaithful husbands. In his new book, "An Unsolicited Gift," he describes the dueling affections at play when boys suckle on two metaphorical teats.
Dr. Dennis Friedman, a fellow of the Royal College of Psychiatrists, theorizes that having two female caregivers subconsciously introduces the child to the "other woman," and to the concept that more than one woman can meet his needs.
"As the British say, this is poppycock," said Michael Diamond, a Los Angeles psychologist specializing in male development and parenting. "It's too simplistic."
American experts say it doesn't matter who is the primary caregiver -- mother, father, grandmother, kibbutz or nanny -- sons need affection with boundaries, friendships with girls and permission to experiment with sex.
"Clinically speaking, infidelity happens much more when the male did not grow up with a healthy model of the relationship in front of him," said Diamond.
Many notorious adulterers didn't grow up with good parent models.
President John F. Kennedy and his brothers had a philandering father, Joseph Kennedy, who slept with starlets and then the son went on to have his own string of infidelities.
Bill Clinton, who used the Oval Office for his highly public affair with intern Monica Lewinsky, had no daddy and an abusive step-father while his mother married five times over.
Tiger Woods, with a cheat sheet as long as his tawdry tale, had too much daddy, a tyrannical father who pushed him in to the competitive world of golf, some say robbing the boy of his childhood.
Other highly public infidelities smacked of the entitlement that can come with money or power.
Eliot Spitzer, who as the "Love Gov" got caught with a New Jersey prostitute, had a classic rich boy resume and, some say, an elevated sense of hubris.
Nanny hater Friedman blames the absent mother, claiming that in adulthood Johnny may seek out the woman who changed his diapers and kissed his boo-boos better to get sexual gratification.
Psychologists don't discount the oedipal theories, especially the so-called Madonna-whore complex.
King of rock Elvis Presley reportedly slept with his young wife Priscilla only long enough to get her pregnant before turning to other women.
"The mother's overinvestment in little boy becomes so seductive to him that he feels that having sex with another woman is, at some level, incestuous," said Diamond.
The "obsession" with cheating seems to be an American phenomenon, according to Cindy Watts, who raised two sons while living an ex-patriot lifestyle in Asia.