The identification of a genetically inherited disease, or a risk of disease, creates a context in which health, illness, risk and susceptibility to disease are subject to definition and redefinition. New genetic technologies may also transform everyday practical understandings of inheritance and relatedness. The chapter examines the experiences of individuals attending a clinical genetics service and their wider kindred, following the flow of information through families. Within this chapter the author presents one family case study (n = 10), using snowball sampling to carry out in-depth interviews with family members, following the flow of risk information from the proband (the first person to attend the clinic) through the kindred. This is done to examine the disclosure practices and exchange of genetic information among kin, which may be withheld or shared as part of the wider network of social relationships and information exchange that constitutes practical family membership. The author examines who constitutes kin, what the dynamics of information exchange are and how individuals negotiate practical decision-making within the context of genetic information and risk.