Some people might try a certain substance or behaviour and never approach it again, while other people eventually become addicted to it. This is partially caused by the brain's frontal lobes. It can also happen due to some chemical imbalances in the brain.
Some mental disorders, such as bipolar disorder or schizofrenia, can lead to developing an addiction.
Genetics also have an influence on addictions. But this doesn't mean that if someone that you're related to used to have an addiction to something, you're automatically going to have one as well. Experts believe that genetics increase the chance of getting addicted to something by about 50 %.
Environment and culture play a role in how you respond to a substance or behaviour. This can either be the environment that you grew up in, or the one that you live in currently. It is an important factor that can help determine whether you're likely to become addicted or not.