Australian Associated Press

One in 25 raise another' s child: claim

AAP, Australia, Aug 11 2005

One in 25 fathers could unknowingly be raising another man' s child, British scientists say.

Researchers at Liverpool' s John Moores University examined the findings of dozens of studies, published over the past 54 years, on cases of paternal discrepancy - where a man is proved not to be the biological father of his child.

The studies, most of them peer reviewed, came from countries as varied as the United States, Finland, New Zealand, South Africa and Mexico.

The findings of the studies varied dramatically - some concluded that only one man in 100 is not the father of his child while others put the figure as high as 30 per cent.

The Liverpool researchers calculated the median figure at around 4 per cent, suggesting that as many as one in 25 men worldwide is not the biological father of a child he believes to be his.

"The importance lies not so much in the figure itself but in the implications, given that as a society we are increasingly making our decisions on the basis of genetics," said one of the researchers, Professor Mark Bellis.

"If, for example, someone knows that their father had a history of hereditary heart disease, they might be tempted to alter their own diet," he said.

"Obviously they need to be making that decision on the basis of accurate information about who their father really is."

Bellis said that while mix-ups of semen during artificial insemination accounted for some cases of paternal discrepancy, the majority were due to a woman having sexual relationships outside marriage.

He said in Britain, 20 per cent of women in marriages or long-term relationships have had affairs, adding that the figures for other developed countries was similar.

Around a third of pregnancies in Britain are unplanned, increasing the risk of paternal discrepancy.

Writing in the British Medical Association' s Journal of Epidemiology and Community Health, the scientists called for further research in the area.

"(We) cannot simply ignore this difficult issue," they said.

AAP 2005