A study from Washington University in the U.S. examines cannabis initiation and use in a group of European-American and African-American twins. Telephone interviews were conducted with 3786 participants in a population-based study of female twins. The study showed that childhood maltreatment was significantly associated with increased likelihood of cannabis initiation before age 15 in both European-American and African-American women. However, an increased likelihood of later initiation was among European-American only. Maltreatment was associated with cannabis problems among both groups.
The researchers concluded that childhood maltreatment is a major contributor to early initiation of cannabis as well as progression to cannabis problems in both European-American and African-American women. Distinctions by ethnicity was not found to be genetic, but in the type of environmental influences that contribute to stages of cannabis involvement.