and ethnicity of their four grandparents. Eighty percent (N=1906 unrelated individuals) of the pooled GWAS sample provided self-report on ancestry and birthplace of all four grandparents. Of these, 95.6% had all European grandparents (with 70% of these Northern European, N=1281), a further 1.7% indicated Australian Aboriginal ancestry and 1.5% reported some Asian or Middle Eastern ancestry. Three who reported ‘Australian’ ancestry are thought to have all grandparents born in Australia but with European ancestry. The remaining 1.1% had one or more grandparent from the Americas, Africa or the Pacific region. All individuals were included in the pooling experiment. All participants provided written informed consent under study protocols approved by the Queensland Institute of Medical Research (QIMR) Human Research Ethics Committee. In total, 9669 individuals from 4882 families, comprising 3115 twins, 5665 non-twin siblings, and 889 parents were interviewed.
