When is a Dad not a Dad? No, that is not a riddle or the beginning of a feeble joke. It is in fact a real question and one that the family courts sometimes have to consider. What defines a father – is it nature or is it nurture ? And what happens if a man one day discovers the children he helped to raise are not biologically his?

Richard Rodwell from Peterborough, made that unwelcome discovery a few years ago.

Now 46, factory manager Richard was married to Helen for 14 years, during which time they had two children, Adam and Laura. When the couple went their separate ways in 2004, Helen was awarded custody and Richard paid £300 per month in maintenance for an additional four years.

Then, reports the Mail on Sunday, things took a sudden turn fort the worse. Mr Rodwell began hearing rumours that Laura, then aged 20, was not his biological daughter. He phoned Helen but she insisted he was Laura’s father. Eventually Mr Rodwell insisted on a DNA test. It was negative.

“When I saw the letter stating that I wasn’t Laura’s father I just broke down,” he remembers. “When I phoned Helen we had an argument and she just said, “What did you expect.” She didn’t even say sorry.”

But it didn’t end there. Another DNA test revealed that Adam was not his biological son either.

Mr Rodwell sued his former wife for deceit and was awarded £12,500 per child. He also won a court order forcing his ex-wife to move out of their marital home.

His solicitor told the paper: “The court treated it as akin to bereavement, awarding a similar sum to the one you would receive if your child died in an accident, which is £11,800. I think in this case, the county court judge went further than that because of the level of deceit and the fact that Mr Rodwell’s new wife is too old to give him children, so he has lost his chance of fatherhood.”

Mr Rodwell does, apparently, see what has happened as a bereavement. He is quoted saying: “I have lost the children I believed were mine. I treated them both as if they were my own. I was there at their births, went to their Nativity plays and helped them with school homework. I can’t stop thinking about the children as they were my life. I always wanted children and grandchildren and now it’s too late in life for me. The children were the most important people in my life, and now they have gone.”

Heartfelt words – but I would say that the children were his own. Not biologically, but he was their father in that every day sense that really counts.

Mr Rodwell claims that his former wife has turned the two children against him since the DNA tests and “told them to keep away from me”, and I cannot help but feel that what he is really mourning here is the loss of his relationship with the children, not the loss of a theoretical biological link.

He even admits that “I would have been happy to have a close relationship with them as a stepfather”.

So called ‘paternity fraud’ is an emotive topic and one I have written about before. Despite hysterical claims, there is still little hard evidence of an epidemic. Clearly it does happen sometimes, and Mr Roswell seems to have been unlucky enough to be a victim. But is he entirely blameless?

We only inevitably incomplete press reports to go on. Yes, it does appear that his former wife was unfaithful and misled him for many years about he paternity of the two children. That is hardly commendable, in fact it is appalling, but Mr Rodwell still chose to push ahead with paternity tests in

the face of “rumours”, despite the relationship he had formed with the children over those many years. What is the point of opening the proverbial Pandora’s Box in such a situation? We do not know what the children themselves thought of this decision.

I do not subscribe to the rather Darwinian views expressed by some readers on the Telegraph that Mr Rodwell was “selected from the gene pool”. It is real relationships in the here-and-now that matter to children. Biology comes a distant second.

There will inevitably be those who will also roundly condemn the mother along with the Judge who found her deceit proven. And her part in this family tragedy should not be overlooked. Sperm donation is legal provided the consent of the husband is first obtained. For whatever reason she however chose to have her affairs behind his back. She has been well and truly named and shamed and he has had his day in court.

But was it all worth it in the end?