17.2.1 Biological Risk Factors

• Genetic vulnerability is the idea that inherited characteristics passed on from parents to children increase the likelihood that someone will develop an addiction
• The genetic vulnerability explanation for addiction thus suggests that a vulnerability to addiction may be genetically influenced
• Research into genetic vulnerability to addiction analyses the genetic structure of the individual and compares DNA sequences of family members to identify genes involved in addiction to a particular substance or behaviour
• Much of the focus of research into genetic vulnerability has focused on twin studies and Family linkage studies
• As MZ twins share 100% of their genetic make-up while DZ twins share only 50%, it allows psychologists to make useful comparisons regarding genetic vulnerability to addiction, measuring the concordance rate
• The likelihood of someone becoming a smoker, gambler or alcohol-dependent is viewed in the context of increased risk if  a person’s parents or MZ twin engage in these behaviours

Research suggests children are more likely to smoke if their parents smoke.

Research which investigates genetic vulnerability as a risk factor

• Kendler et al. (1997) conducted a longitudinal study over 40 years and found that the concordance rates for alcohol abuse in a large sample of almost 9,000 Swedish MZ twins were consistently significantly higher than for DZ twins, suggesting a genetic component
• Slutske et al. (2010) found that MZ twins had a higher concordance rate for a gambling disorder (49% for male pairs and 55% for female pairs) in comparison to DZ twins (21% for male pairs and female pairs), suggesting genetic vulnerability was partly responsible

Evaluation of research investigating addiction

Strengths

• There is  a large amount of twin and family research supporting the explanation of a genetic vulnerability to addiction
• Some research suggests that inherited personality traits may be responsible for addiction with novelty-seeking being positively correlated with genetic markers for the D4 dopamine receptor and also with addiction to alcohol, which broadens the support for genetic vulnerability (Ray et al, 2009) 

Weaknesses

• MZ twins are more likely to be treated similarly by parents than DZ twins, meaning that concordance rate differences may be the result of upbringing rather than genetic similarity, weakening the argument for a genetic vulnerability to addiction
• There are many other factors which affect the predisposition to addiction such as exposure to the drug, availability, stress, family influence and peers, so genetic vulnerability remains an incomplete explanation

Link to Approaches:

The role of genetic vulnerability in addiction is researched using a Biological Approach, as the explanation focuses on genetically inherited characteristics. Research is mainly by twin and family studies, looking for concordance rates for substance dependence between family members.