One in 25 fathers may not be child's dad

An outbreak of male paranoia is guaranteed today with the disclosure that one in 25 fathers may be unknowingly raising a child who is not their own.

A review of studies of DNA profiling, the ultimate proof of a genetic relationship, shows that the rate of "paternal discrepancy" - where the man tested is not the actual biological father of the child - ranges from 1 per cent to 30 per cent.

Researchers from the Centre for Public Health at Liverpool John Moores University say the average rate is 3.7 per cent, equivalent to almost one in 25 fathers who discover they are not the true fathers of the children they call their own.

The revelation can be devastating for families but the implications have not been understood, the authors of the study, published in the Journal of Epidemiology and Community health say.

In the UK around a third of pregnancies are unplanned and one in five women in long-term relationships has had an affair.

The total number of families affected will be much higher than one in 25, the researchers say, because for every "false" father identified through testing there will be a true biological father elsewhere, possibly with a family of their own.

DNA testing is increasing rapidly and the judicial and health systems are reliant on it for procedures such as organ donation and criminal identification.

In some cases, such as disasters in which people have died, the tests have unwittingly revealed some with a different biological identity from the one suggested by their credit cards, clothes and personal possessions, adding to the distress of surviving relatives.

Professor Mark Bellis, chief author of the study, said: "We know infidelity breaks up families. Around 20 per cent of divorces feature claims of infidelity by one or both partners. There are issues around the mental health of the father, or the person who thought he was the father, as well as the woman and the child in the family."

"More and more people are taking these tests and they may receive some of the most fundamental information about themselves and their closest relatives for which they are unprepared. We have not looked at the consequences of giving this information - or of with-holding it."

The impact of paternity testing was brought home during the public break-up of the relationship between former British Cabinet minister, David Blunkett, and his former lover Kimberly Quinn, after he demanded access to the child whom testing proved he had fathered.

Several soap operas, including the now defunct Liverpool series Brookside, have featured plot lines about disputed paternity and the Human Genetics Commission has expressed concern after the results of paternity tests were broadcast live on ITV's Trisha show.

DNA testing can be carried out on a small sample of cells taken from a hair follicle or scraped from the inside of the cheek and is available by post from commercial agencies.

There are no figures for the UK but demand for tests is rising. In the US they leapt from 142,000 in 1991 to 310,490 in 2001.

In some cases fathers have tested children without the knowledge of their partners, with unpredictable consequences. The discovery of a discrepancy can be a trigger for domestic violence or lead to neglect of the child.

Some countries are considering introducing legislation to outlaw genetic testing of children without the consent of both partners but it is unlikely to be effective because many testing agencies are based overseas.

Professor Bellis said genetic testing was not bad in itself because three quarters of couples received reassurance that they were the biological parents of their children.

"These people have their minds put at rest - so it is a valuable service," he said.

"But for others it may have all sorts of implications including financial ones in terms of child support."

- THE INDEPENDENT