It has been suggested in some studies that up to 10 percent of fathers are not the biological parents of their alleged child, but how this differs across cultures and to what extent men's paternity assessments reflect actual biological paternity is not well known. The author says that paternity confidence has important implications for a man's involvement with his children, since men are less likely to interact with and support children whom they do not believe to be theirs.
In his study Anderson compared the paternity test results for men with high confidence regarding their paternity to the results for men with low confidence hoping to determine how the perceptions of fatherhood correlate to the fact. He found that, men who were confident about their fatherhood undergoing the test were only wrong 1.7% of the time, meaning they were indeed the child's father more than 98% of the time. As compared to men who were in doubt about their fatherhood, specifically men who contested paternity through paternity tests were more frequently not the fathers of the child, in about 29.85 of cases. Meaning that more than 70 percent of the time, men who doubted their paternity were wrong.
Anderson also organized the data geographically, by breaking down non-paternity rates in different countries according to high and low paternity confidence. He found that among those for who paternity confidence was relatively high, actual non-paternity is highest in Mexico and lowest among the Kohanim lineages of Sephardic Jews.