In rather disconcerting news, it appears that as many as one in 25 fathers, could unwittingly be raising another man's child.
When researchers at Liverpool's John Moores University examined the findings of dozens of studies, most of them peer reviewed, on cases of paternal discrepancy, the results varied dramatically.
The studies, published over the past 54 years, came from countries as varied as the United States, Finland, New Zealand, South Africa and Mexico.
Apparently some concluded that only one man in 100 is not the father of his child, while others put the figure as high as 30 in 100.
The Liverpool researchers estimated the median figure to be around 4 percent, and suggest that as many as one in 25 men worldwide is not the biological father of a child he believes to be his.
Professor Mark Bellis of the research team, says, in view of the fact that as a society we are increasingly making our decisions on the basis of genetics, the implications are cause for concern.
He says that if for example someone knows their family has a history of hereditary heart disease, they might be tempted to alter their own diet, and obviously such decisions should be made on the basis of accurate information.
According to Bellis 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.
In Britain, it seems that 20 percent of married women or those in long-term relationships, have had affairs, and the figures for other developed countries are similar.
As around a third of pregnancies in Britain are unplanned, the risk of paternal discrepancy is increased.
The scientists are calling for further research in this area, and say this difficult issue cannot be ignored.
The report is published in the British Medical Association's Journal of Epidemiology and Community Health.