Around one in 25 men could be unknowingly raising children to whom they are not biologically related, say UK researchers. The team, based at Liverpool John Moores University, has reviewed previous studies to estimate the rate of 'paternal discrepancy' worldwide. They found that the proportion of families in which a man is not the biological father of his child ranges from less than one per cent to as much as 30 per cent. The researchers say their findings, published in the Journal of Epidemiology and Community Health, have 'huge' implications for the use of genetic testing in forensic and health settings.
The team based their results on 17 papers and conference abstracts published between 1950 and 2004. They estimate that the median rate of paternal discrepancy revealed by these studies is 3.7 per cent, affecting about one in 25 fathers. However, the researchers say that the increasing use of DNA techniques in judicial and medical procedures, as well as an increase in paternity testing, means that this figure is set to increase. They warn that disclosing non-paternity can lead to family break-ups and violence, but that leaving paternal discrepancy undiagnosed could mean that people will infer incorrect medical information.
The studies reviewed came from several countries, including the US, Finland, New Zealand, South Africa and Mexico. The importance of the four per cent figure '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', according to team leader Mark Bellis. 'If, for example, someone knows that their father had a history of family heart disease, they might be tempted to alter their own diet', he said, adding 'obviously they need to be making that decision on the basis of accurate information about who their father really is'.
In the UK, demand for paternity tests has increased tenfold in the last ten years, with somewhere between 8,900 and 20,000 tests being carried out every year, according to paternity testing firm University Diagnostics. And in the US, the number of paternity tests has increased from 142,000 in 1991 to 310,490 in 2001. The results of such tests are not always delivered with the necessary support and counselling, says Bellis. Adrienne Burgess, of Fathers Direct, told BBC News Online that a code of practice should be put in place to ensure that companies offering paternity tests also offer counselling.