Genetic Involvement A1

The classical approach to teasing out whether genes contribute to a complex behavioral trait is to examine whether the trait co-occurs in monozygotic (identical) twins. If for example, the trait occurs in 100% of identical twin pairs who have been reared apart (i.e., in different environments), then the trait is probably entirely genetic since identical twins share 100% of their DNA. These types of family studies, along with epidemiological investigations suggest that 40 to 60% of an individual's risk for addiction to alcohol and most illicit drugs is genetic. Similar estimates come from the study of addiction in rodents.

Occurs due to the genes of the molecular receptors being altered.

1. How exactly are the receptors being altered?
   

AskBig.com. 2006-2007 Institute For Genome Sciences & Policy. December 6, 2006 http://www.askbig.org/archives/a-z/addiction/