By Georgina Burrows

The secret of a happy marriage, according to scientists, is for a wife to be smarter and at least five years younger than her husband.

Researchers have developed a distinctly unromantic formula to predict how compatible a couple are, based on their ages, education and relationship history. Those most likely to stay together are couples in which the woman is more educated than the man. He, however, should be five or more years older – and neither should have been divorced in the past.

Academics, including Dr Emmanuel Fragniere of the University of Bath, studied interviews of more than 1,500 couples who were married or in a serious relationship. Five years later, they followed up 1,000 of the couples to see which were still together. From this they were able to assess the factors that create a successful partnership – and those that spell failure.

Meanwhile, a survey conducted by Glasgow University has found that having children makes you happier – contradicting a host of other studies which have concluded that having children can ruin even the most blissful of relationships. Instead, it seems, the patter of tiny feet strengthens a partnership – but only if the parents are married. If a couple are simply living together, the birth of a child tends to bring discontent.

Well, all I can say to these findings, published in the media this week, is to quote Charles Darwin with the words "It is not the strongest species that survive, nor the most intelligent, but the ones most responsive to change." More pertinently, I would add that if a happy marriage was as simple as choosing a partner who fitted the “formula” or deciding to have children then divorce lawyers would be going out of business pretty quickly!

Quite obviously that’s not the case. And the reason for that is quite simple: every couple’s relationship is unique. A marriage that looks sound “on paper” can founder, while a partnership that appears doomed to failure can flourish in the face of statistical evidence. It is those couples most able to adapt to changing circumstances together, such as the arrival of children or even financial difficulties brought about by redundancy, who are most likely to “survive” their marriage, whether the wife is older or younger, more intelligent or less intelligent, they have children or don’t have children.

I have a real problem with surveys that claim to know what relationships work best. Not just because you can’t apply a scientific formula to a human partnership, but also because such studies serve only to heap guilt on to those people whose marriages haven’t worked out because scientists say they have made a “wrong” choice.

No one opts for divorce lightly. People go their separate ways because the relationship isn’t working and usually it takes many months and even years of being unhappy and trying to make things work before that difficult decision is made. If after taking steps to resolve problems a marriage still isn’t working, it’s best to get out.

Formulas and statistics might give researchers an idea of what keeps couples together – or cause them to split up – but they don’t take into account the vagaries of life that can make or break a marriage.

• Georgina Burrows is a children law specialist at Benussi & Co