I had to chuckle to myself when I read  the reported data on infidelity in Richard A. Friedman’s essay, “Infidelity Lurks in Your Genes” in the NY Times Sunday Review, May 24th. Friedman quotes from a survey by Brendan P. Zietsch, a psychologist in Australia who wrote: ” 6.4 percent of women reported that they had two or more sexual partners in the previous year”. Zietsch apparently assumed that the number of sexual partners  could be used as a working definition of infidelity.  It may not be that simple.  In the effort to quantify the data, Zietsch and by association, Friedman, may have overlooked a percentage of the female population and  thereby may have left out a significant aspect of infidelity. Here’s why.
    A patient told me that at her annual physical exam the nurse asked  if she were married. She said yes. The nurse then asked;” So you have only one sexual partner, is that correct?”  My patient answered yes; but the nurse erroneously assumed that was the end of the discussion– it really wasn’t.  Since the nurse didn’t ask any further questions, my patient allowed her think the obvious.  The obvious wasn’t so obvious because my patient’s only sexual partner is her lover, not her husband.  After many years of a sexless marriage, and the loss of self-esteem being undesired by her husband, this woman decided not to live the rest of her life celibate. Would Zietsch and Friedman have considered this a case of infidelity? Using Zietsch’s definition,  it would not be counted as such.
I wonder how his  conclusions would have been effected had he asked the women who reported only one sexual partner if that partner was, in fact, their husband.  If this question had been added to the survey, it might have changed the findings about the impact of genes on infidelity.