Data from 443,693 participants from four different data sources were used, including the Queensland Twin Registry's “25 and Up” (25Up: N = 2,133) study in Australia, 33 “Spit for Science” (S4S: N = 2,994) study in the USA, 34 the “Netherlands Twin Register” (NTR: N = 12,120) repository in The Netherlands, 35 and the “UK Biobank” (UKB: N = 426,446) in the United Kingdom. 36 Although 25UP and S4S are considerably smaller than the others, they have not been included in previous risk behavior GWAS and have data on phenotypes that were not available in NTR and UKB, making them valuable additions. All studies were performed in accordance with the Declaration of Helsinki and were approved by local ethical committees. Study details are described in articles referenced in the Supplementary Methods section.
