The most reliable test for paternity is genetic testing, also known as DNA testing. Requirements for consent and counselling vary by country. However, genetic testing is based on probabilities and is not always definitive. Jones et al. (2010) said, "Characteristics of the markers and the fact that they are analysed by fallible humans can result in inconsistencies that present problems for parentage analysis." False negatives may occur due to low quality samples, gene mutations, or genotyping errors (when a genotype is misread or inaccurately scored). There is a higher probability of accuracy when DNA from both parents can be tested. The accuracy increases even more when DNA from a sibling is available. It is difficult to accurately estimate the incidence of misattributed paternity, and there have been large discrepancies in the research published on the topic. Often data on non-paternity rates are reported tangentially to the primary goal of research without sufficient detail, and very few studies involve randomized samples. As such, it is not possible to make valid generalizations based on a large portion of the available literature. Bellis et al. (2005) found that between 1950 and 2004, the rates of misattributed paternity published in scientific journals ranged from 0.8% to 30% with a median of 3.7%. According to a study published in the "Lancet", "High rates have been quoted, but are often unsupported by any published evidence or based on unrepresentative population samples." Turi King and Mark Jobling of the Department of Genetics at University of Leicester called the commonly cited 30% rate of non-paternity an "urban myth". According to King and Jobling, the figure is around 2%. They also stated that misattributed paternity is often impacted by cultural and socioeconomic factors and that it occurs more frequently among couples who aren't married. Sociologist Michael Gilding concluded that inflated figures have been circulated by the media, the paternity testing industry, fathers' rights activists and evolutionary psychologists. He traced many of these overestimates back to a 1972 conference where non-paternity rates as high as 30% were discussed. Gilding states that these data only show the incidence of non-paternity in cases where disputed parentage was the "reason" for paternity testing. In situations where disputed parentage was the reason for the paternity testing, there were higher levels with an incidence of 17% to 33% (median of 26.9%). Most at risk of parental discrepancy were those born to younger parents, to unmarried couples and those of lower socio-economic status, or from certain ethnic and cultural groups.