When is it amoral to have an affair, no matter whether it be a one night stand or something a little meatier?

The other day I caught a story in which a rather crestfallen man discovered, by chance and DNA testing, that all four of his children had been fathered by other men! His wife, during ovulation, had sought out partners of a particular genetic profile. It was probably not conscious, more a driving need but she gave way to it on four separate occasions. One thing is for sure, something about the make-up of her husband’s cells sent her scurrying for something different!

Once, when I did some consultancy work for a hospital management team, I was told by midwives that anecdotal knowledge, accumulated over time, suggested that between one and two in every ten children are not born of their legal fathers. The official figure is one in ten. Women of all walks of life, rich or poor, are fully capable of breaking the bonds of happy matrimony and playing the field.

This is a paradox at the heart of societies. While the majority uphold social conventions regarding the sanctity of families, they can still be susceptible to their loins and then their logic gives way to illicit sex and bastard offspring. The rather poignant point of their behaviour is that their genes override everything conventional in their attitudes and set them on this course towards extra-marital promiscuity, for entirely worthy reasons.

The cause of their philandering is that they ‘sense’ that their partners’ gene pools are not sufficiently different from their own to be certain that their offspring will be healthy. In an experiment to show this, women and men were asked to sniff the tee shirts of members of the opposite sex and rate them according to their attractiveness to them. The pattern of results showed, unequivocally, that they rated the tee shirt which was most dissimilar from their own gene profile as the most attractive.

It doesn’t matter whether you are male or female but you have this sense of which you are consciously unaware. Let’s call it genetic sensitivity. Could it be a defence that might stand up in a court of law? As Richard Dawkins suggested in The Selfish Gene, could we argue that in certain circumstances we are not of sound mind, we are at the behest of our DNA? Should we even allow divorce on the grounds of a woman’s infidelity when she is driven by altruism rather than lust? Seeking an unalike genetic partner must be a biological imperative to ensure that her own genes and those of humanity, as a whole, prosper, thus reducing the opportunity for malfunctioning DNA to weaken the population.

This must be the true meaning of the French maxim, vive la difference!