One in 25 fathers may not be the biological parent of the child they believe to be theirs, according to a study published today.

Its authors say governments and society have not woken up to how DNA testing and genetic profiling are lifting the lid on a "Pandora's box" of hidden sexual behaviour or how the results might affect individuals, family relationships or public health.

Their review of estimates of so-called paternal discrepancy over more than 50 years suggests the father was not the natural parent in between 1% and 30% of cases.

The team from Liverpool John Moores University agreed that the figures, drawn from studies of men and women seeking proof of paternity, might be exaggerated because uncertainty over fatherhood is usually the reason for tests.

But other studies, such as those based on genetic health screening, might underestimate the level of mistaken fatherhood because people can refuse to participate or are excluded when paternity is in doubt.

Studies based on populations not being tested for paternity suggested a 3.7% rate, said the authors, but accurate figures were needed for Britain, where about a third of pregnancies are unplanned and one in five divorces cites infidelity by one or both partners.

The researchers point to US increases in paternity tests from 142,000 cases in 1991 to 310,490 in 2001. The London firm DNA Bioscience said research suggested between 8,900 and 20,000 tests a year are done in this country, 5,000 of them on the orders of the Child Support Agency.

Of the remainder, 10% were instigated by adult children looking to confirm parentage and the rest fathers seeking confirmation.

The John Moores team, headed by Professor Mark Bellis, raised the issue in the Journal of Epidemiology and Community Health. "For any father, identifying that the child they are raising is actually sired by another man can have substantial health consequences.

"Such knowledge can also destroy families , affecting the health of the child and mother as well as that of any man who is subsequently identified as the biological parent."