asked similar questions, that is, whether “drinking ever caused your biological (mother/father) to have problems…,” and whether they were an “excessive drinker.” Endorsement of both problem and excessive drinking was required to code a coparent positive by twin report (in PACER) or offspring report. Neither MATCH nor PACER interviews included assessment of cannabis dependence symptoms experienced by biological coparents; instead, coparent recurrent use was coded from twin or coparent report, defined as lifetime use of cannabis on 11 or more occasions. Parental cannabis use was not assessed by offspring report. Given 15% missingness, two dummy variables were coded to distinguish coparent recurrent use from missing coparent cannabis data, with coparents having never used or used on less than 11 occasions comprising the reference group.
