More men should spend more time staying at home with more children - or so claims Harriet Harman, the Minister for Women. Indeed, she suggests in visionary manner, it should be the norm that mothers and fathers both spend equal time working and raising children, and the only thing presently preventing this idyll is that “most fathers simply don't know or take advantage of their rights”.

In other words, evidently unfamiliar with the practice of leading horses to water, Ms Harman believes that if only flexible workplace hours were routinely available, men would rush to take advantage of an equal opportunity to sit at home smeared with baby sick.

Fat chance. The reason that this change won't come about has nothing to do with availability and everything to do with a choice that to a great extent already exists and to a greater extent has already been declined. Men don't spend more time with their small children because they do not wish to do so. Babies, infants and toddlers create unbearably hard work - far harder than, say, taking executive decisions in air-conditioned offices - and nobody in their right mind would opt to do it.

It is one thing to come home to a freshly bathed, pyjama-clad bundle whose welcoming giggle reveals the advance of a new toothie-peg through a pearly pink gum, ooooh, who's a very clever little girl then? It is quite another to have spent the day soothing the fractious pain of it, pushing mushy food through wailing jaws and having it spat right back again. To admire a few first, tentative steps on a Sunday morning is not the same as having every small, daily errand walked at the snail's pace of an accompanying two-year-old. To listen occasionally to a “choo-choo” or (best of all?) a “Dadd-da” is light years from such eloquence setting the standard of all the conversation enjoyed in an entire day.

Engagement is boring; disengagement - even turning your back for a second - too risky to contemplate. Guilt, inadequacy and exhaustion conspire to swamp the full-time carer for whom the real world is a distant, wistful memory. And men know all of this. Which is why no amount of politically inspired social engineering, on Ms Harman's or anybody else's part, is going to prevent them passing the buck that is and will remain theirs to pass. It is not their day job that most of them want to do part-time; it is their parenting.

Women, of course, know the rigours too. Happily for the survival of the species, however, they don't have a buck to pass; that was stolen from them by the surge of hormonal insanity that accompanies the early rumbles of pregnancy, through the strains of labour and into the first dripped drop of a mother's milk... a surge quite irrational, but so powerful that they actually have no choice at all. Praise be.

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