Public understanding of the new genetics is often criticized in discus
sions about the social and ethical issues the new genetics raise. In t
his paper we challenge the ''deficit model'' evident in this dominant
discourse, and offer a constructivist approach. We explore lay experti
se about the new genetics, presenting an analysis of data from ten foc
us group discussions with a range of lay people. After distinguishing
four different types of knowledge lay people hold-technical, methodolo
gical, institutional, and cultural-we go on to consider how lay people
's mobilization of this ''stock of knowledge'' is influenced by social
location and social context, exploring in particular interviewees' pe
rceptions of relevancy. We conclude that identifying lay people as exp
ert in, rather than ignorant of, the way genetics may shape their live
s is a fundamental first step in moving toward greater lay participati
on in policy discussions and, ultimately, decision making about the ne
w genetics and health.