Scientist are saying that people who just can't go a day without taking a sniff of marijuana aren't doing it because they want to get high, but also because there is an addiction gene in the plant. A recent Yale study may have identified the specific genes involved in cannabis dependence (CAD).
via The Daily Beast:
“We showed that risk for cannabis dependence is affected specifically by certain risk alleles and these risk alleles fit biologically with some of our existing ideas of the nature of cannabis dependence,” Dr. Joel Gelernter, senior author of the study and a Yale psychiatrist, told The Daily Beast.