This study is the first to characterise the type of people trying to resolve unknown parentage cases in the UK and Ireland, and how successful their efforts are, using commercial DTC (direct-to-consumer) DNA tests. A survey was conducted of individuals born in the UK or Ireland, or with a biological parent from the UK or Ireland, who had used genetic genealogy as a part of their search for one or both biological parents. Success rates were high, with DNA assisting the identification of a birth parent in 48% and 55% of cases (48% for those with unknown fathers and 55% for those with unknown mothers). In an additional 20% and 21% of cases (unknown fathers and unknown mothers respectively), DNA identified grandparents or more distant ancestors. The majority of those identifying a biological parent did so within six months of receiving their DNA results (39% and 55% of cases), and within two years, 78% and 87% had identified a biological parent. The survey also attempted to assess the likelihood of success of the combined use of GEDmatch and FamilyTreeDNA in IGG (investigative genetic genealogy) cases in Britain and Ireland and found that potentially IGG-suitable matches were present in about 60% of cases. These results complement those of earlier studies and have important implications for social policy in the UK and Ireland.