Does having children increase our happiness? The question answers itself, doesn’t it? Or does it? As I write, the grandchildren are out. The twin five-year-olds are over with their mother from America. How lucky we are in the golden moments. But with that luck come certain penalties: noise, mess, a collapse of household routines. Much of that comes from the fact that our way of life has developed to suit two people just 70 years older than the twins. But it does bring home, and with some force, the very different demands which the parenthood of young children makes.

There have been many studies on whether children contribute to happiness in marriage, and the evidence is mixed. But the broad direction of the results, based on the subjects’ self reports is, I fear, negative. An example comes from Dr Nattavudh Powdthavee of York University. He says: “Social scientists have found almost zero association between having children and happiness. In a recent study of British adults for example it was found that parents and non-parents reported the same levels of life satisfaction. Other studies from Europe and America found that parents report significantly lower levels of satisfaction than people who haven’t had children.”

It is not hard to see why.

Review the lifestyle of a childless couple, each contributing an income and each having a whole personal universe of their career with its fulfilments and social connections. They have the possibility of a quiet, intimate life together, enjoying the material standard of living which their earning power provides. They can have a mutual social life and share, if they choose, in the voluntary good works which their resources make possible.

Contrast this with the parents of a family. For some periods, at least, only one income is available – and over lengthy periods total income is likely to be reduced since one earner can probably make little career progress and may be working part-time. Total up the cost of children in terms of lost earnings and additional expenses and the sum will be calculated not in thousands of pounds but in the difference between a comfortable pension and a straitened old age. There is little quiet in the house from morning to night – and the sound is not invariably that of children’s happy laughter.

The weekends, or the evenings, may well be taken up ferrying children hither and thither. Opportunities for privacy are few and far between. Since children do not have their illnesses collectively but seriatim, it is possible to go throughout an entire winter without have a single day free of at least one child with a temperature.

Nor, at the end of it all, can you be certain that the result will be a happy brood of adults effusive in their thanks for parenting them at such sacrifice. It is more likely that at least some will be much more conscious of what they perceive as your shortcomings. Do not expect gratitude from your children. And do not expect that you can ever divorce yourself emotionally from the troubles of your adult children. You can’t.

In western society, these differing lifestyles are now standing out in sharper contrast. The average age at the birth of the first baby has risen by four or five years and that means that the habits of independent income and unfettered social life have become well established before they are replaced by the spartan regime of motherhood. About 19 per cent of women aged 50 in Britain have eschewed parenthood – almost twice the percentage of the 1990s. Parenthood used to be the default option for marriage, now it is a rational choice of lifestyle.

Of course the concept of happiness is controversial. In a rather superficial sense one might define it as the difference between our expectations and our experience. If we have consciously undertaken the task of procreation with a good understanding of what is involved then the happiness, or perhaps satisfying sense of fulfilment, will follow – even if we have sometimes to experience it through gritted teeth. While I was well aware that the costs and the trials of our largish family lowered our standard of living in certain respects, I was always clear that, if I took my life as a whole, I was ahead of the game. And when this year we were able to catch in one photograph all our 14 grandchildren, aged from five to 24, our deep happiness was very special.

Fortunately I am not alone. At any given moment a parent can be mired in the tribulations of the family – yet never doubt that it is worth it. And our admiration for the David Camerons of this world who have tended a child through the whole length of this vale of tears is unbounded. If he has taught us nothing else he has taught us about unconditional love.

As I argued in this column on March 26, we are already well set on a course which will lead the human race towards extinction. It does not require plague, global warming or nuclear war, just millions of small decisions not to have children. As the psychologist David Gilbert wrote: “Imagine a species that figured out that children don’t make you happy. We have a word for that species: extinct.”

Perhaps the saddest thing is that the Church – the great champion of abundant life – sounds a trumpet which nobody hears. For this generation, and perhaps for generations to come, its endemic preoccupation with sexual sin, and the treacherous behaviour of so many in authority, has rendered its message impotent.

Or am I too pessimistic?