Twins were interviewed between 2006 and 2009; a total of 3326 twin individuals completed the full interview. Of these, 2276 (69% of 3302; 24 missing) reported lifetime (ever) cannabis use. The final breakdown of the sample, including gender and zygosity is presented in Table 1. The mean age of the final sample was 31.9 (SD=2.5), ranging from 27–37 years.
