There is no fool-proof way to predict who will become addicted to drugs and alcohol or not. There are many factors which influence whether someone will use substances a few times and be able to stop and those who develop a problem with their use. For instance, some people are able to experiment during their college years, but will not end up with a debilitating problem. Others will just use a few times and early-on will show signs of an addiction.

There are three main areas though that influence whether someone will develop an addiction or not. These include the person's genetic make-up, their environment of friends and family, and their age and stage of development at first use. If a person has all three risk factors they are more likely to become addicted than if they have just one risk factor. Genetics Drug and alcohol addiction clearly has a genetic component. Addiction tends to run in families. The more genetic code you share with an addicted family member the more likely you are to have an addiction. Additionally, if both your mother's and father's side of the family have a history of addiction, you are more likely to develop an addiction. Genetic factors account for about 50% of a person's vulnerability toward developing an addiction. No one gene is responsible for the tendency for addiction to run in families. Instead, it seems that a variety of traits and biological responses that are passed down work together to influence the development of an addiction. For instance, a person may have a biological tendency to enjoy risk. Their brain may reward them for engaging in risky behavior. But they also may have a biological tendency to act impulsively. Their brain circuitry might respond more quickly than others. These two factors together may then influence a person to engage in risky, impulsive behavior more often such as drug use. There also may be genetic differences in people's experience of addictive chemicals. Biologically, some people may get more of a reward from using substances than someone else. Additionally, some people have a greater genetic risk to develop mental illness. Issues such as depression, anxiety, or bipolar disorder can make people more vulnerable to self-medicating through the use of drugs or alcohol. All the factors that influence the genetic component to addiction are not clearly known, but it is likely that several genetic traits work together to influence addiction.

Environment A person's social context can also affect their tendency to develop an addiction. Someone who has grown up in an abusive or chaotic home is more likely to use substances. Substance abuse can be a means to escape from reality, and if real life has been unpleasant in the past there will be a greater drive to escape. Some family environments teach their children how to cope with stress and negative feelings in a healthy manner. Other families do not provide those resources to their families, thus leaving their children vulnerable to cope by using alcohol or drugs. Furthermore, healthy use of substances may not be modeled in the home. If it is normal within the household for people to get drunk often, a child will feel less tension about getting drunk frequently. The person's current environment also influences the probability of an addiction developing. If a person is experiencing stress or depression, they are more likely to develop a problem with substances. When work is stressful and marriage is not going well, the tendency to use substances increases. If someone surrounds themselves with friends who are drinking or using drugs they are more likely to use. Friends can normalize behavior that is deviant. Peer pressure can affect the development of an addiction, and, in a related way, someone's sense of self-worth, confidence, and self-efficacy influence whether or not someone can resist peer pressure.

Stage of Life Some stages of life are more conducive to substance use and abuse. During adolescence the frontal lobes of the brain lag behind the rest of brain development. The frontal lobes control such functions as self-control, judgment, and decision-making. Thus adolescence can be a vulnerable period for people to engage in behaviors that lack sound judgment, such as drug or alcohol abuse. This is dangerous because the earlier that a person first uses alcohol or drugs, the more likely they are to have an addiction. If alcohol or drug use started early, it is more likely to be an important part of the person's coping skills. If someone learned to deal with social stress in junior high school by using alcohol, they did not get the chance to learn other ways of handling stress as well as they should have; thus, they will continue to exhibit an over-reliance on substances to deal with uncomfortable feelings. Adolescence is a time when people begin to establish their identity. If a person used substances heavily during this time, it is likely that they see substance abuse as a part of who they are. Until the person develops a new sense of identity, their substance abuse problem will be difficult to overcome.