The least surprising survey results I have read for some time were released this week by the Open University, which recorded that couples without children had better relationships than those with them. Surely, no one but a lunatic expects the arrival of children to improve their relationship. Children are probably one of the main causes of divorce. They take up the energy that either parent, or both, would otherwise give to one another. The more children you have, the more true it is.

However, it is also telling that the survey shows that mothers, at least, are a lot happier as individuals then childless women – even if the childless woman happens to have a better relationship with their partner. Men with children, on the other hand, are more likely to be unhappy than men in relationships who don't have them.

It seems that for women, having children more than compensates for the hobbling of their adult relationship. For men, having the attention switched away from them towards the children represents a bigger blow than it does for women. Perhaps it's an ego thing, or perhaps the consequences for men, often greater financial pressures, less sex and being pushed down the pecking order, are not made up for by the decidedly mixed blessing of children.

And it is mixed – whether you are a woman or a man. Anyone who tells you otherwise is either a fool or a liar. Children are the most wonderful, awful, selfish, giving, kind, cruel, beautiful, cantankerous creatures in the world. They push you through the mill until you think you can't take anymore, then they redeem themselves by being the extraordinary forces of nature they are, holy and, at times, verging on the diabolic. Simply by existing, they subtract as well as add to your relationship with your partner – more the former than the latter, as my experience and the survey suggests.

I don't think anyone can make a judgment on whether children "make you happier" or not. Such a statement presupposes that "happiness" is something you possess or don't possess, like furniture. In fact, happiness is a sort of vibration across a spectrum that cannot be quantified, and endlessly changes, and comes and goes. To decide whether you are happier in one state or another is entering the realms of the mathematics of the impossible.

This can be said though: having children represents another realm of experience to not having them, a different kind of universe. No one who does not have children can truly know what it means to have them, for good or bad. And people who have children can't properly remember what it was like before because parenthood changes them so much that there is no firm ground from which to view the past.

A childless couple can mark an emotional graph of a register between one and 10 against a couple with children, but the results are meaningless because the joys of being alone with your partner and being with your partner in a family are so qualitatively different that they can't be compared.

Have my four children made me happier than I would otherwise have been? That is impossible to say. But I know that for all the pressures they put on a relationship, they are greater factories of joy than anything I ever experienced when I was single, just as those difficulties and anxieties of being a parent have produced great depths of misery.

Parenthood is not the soft option or the safe option – it is the extreme option. For those who just want to be content, they should stay childless. For those who want both heaven and hell, children are the solution – as well as the problem.