Is there a type of person more likely to be a drug addict?

A number of factors apply. People with a familial history of addiction are more prone to addiction. People with easy, unfettered access to addictive substances are more at risk than the general population, such as people that work with Anesthesia. People with addictive personalities, that such as risk-takers, thrill seekers, escapists are more likely to become addicted.