Phenotype data from this study were collected as part of the Nicotine Addiction Genetics study (NAG), for which families were targeted based on heavy smoking index cases identified in previous interviews and questionnaires.43,44 Personality items, from the NEO-FFI, were included in a questionnaire mailed to all participants. Genotype data came from the Interactive Research Project Grants (IRPG). Valid personality and genotype data were available for 1 349 individuals aged 21-85 years (M=45.4; SD=13.1). Of these, 56% were women (M=45.4, SD=13) and 44% men (M=45.3, SD=13).
