Anecdotal evidence suggests that the popular pastime of exploring one’s family history can unleash strong emotions, both positive and negative. The aim of this study was to chart the extent and nature of negative emotions among family historians, and profile those most vulnerable to distress. Data from an online survey of 775 adult Australian hobbyist family historians showed nearly two-thirds experienced strong distressing emotions such as anger, shock and sadness while researching their forebears. Triggers included discoveries which led to feelings of betrayal and distrust or posed moral dilemmas. Also distressing were findings about ancestors who behaved badly, were treated cruelly/unfairly, or who experienced tragedy. Family historians who reported strong negative emotions were more likely than those who did not to be younger, female, spend more time on their hobby, have half-siblings, driven by the motive for greater self-understanding, and score higher on the personality trait of openness to experience but lower on emotional stability. The study is important because it raises issues of (a) what support is available to family historians who find their discoveries strongly distressing and (b) whether purveyors of genealogical research products should provide more education and support to their clients.