the speed limit on the motorway?”, with possible responses ranging from “[1] Never/rarely” to “[4] Most of the time.” We dropped individuals who answered “[5] Do not drive on the motorway,” and then we normalized the categorical variable for males and females separately. Our drinks per week phenotype was constructed based on responses to a series of questions about drinking habits and is defined as the number of alcoholic drinks consumed per week. Our ever-smoker phenotype in the UKB is a dummy variable that equals one if a respondent reported being a current or previous smoker and zero if the respondent reported never smoking or only smoking once or twice; our ever smoker phenotype from the TAG Consortium is the Consortium’s “smoking initiation” phenotype (which TAG also refers to as “ever versus never regular smoker”)44. Our number of sexual partners phenotype is based on responses to the question: “About how many sexual partners have you had in your lifetime?”; respondents who reported more than 99 lifetime sexual partners were asked to confirm their responses. We assigned a value of zero to participants who reported having never had sex, and we again normalized this measure separately for males and females. Our
