This paper discusses the changing relationship between population genetics, family genealogy and identity. It reports on empirical research with participants in a genetic study who anticipated that personal feedback on the analysis of their donated samples would elucidate aspects of their own family genealogies. The paper also documents how geneticists, building on the practices of offering personal feedback to research participants, have developed genetic tests marketed directly to people wishing to trace their ancestry. Some of the social and ethical issues raised by this development in the use of genetic testing are considered.