Anyone can become addicted to drugs, but there are a number of factors that can tip the scale in favor or against developing a substance abuse addiction. About half of the risk for drug abuse comes from genetic predisposition, that is to say the genes that you inherit from your parents. Drug addiction can be said to be the confluence of environmental and genetic factors. The environment compromises the setting in which a person grows up in and finds themselves in, the habits of their peers and family.
Mental illness and personal struggles also play a part in causing people to turn to substance abuse to cope with their mental illness or difficult circumstances.
There is no single factor that can predict to a certainty whether or not an individual will develop a substance abuse addiction in their lifetime. Environmental and genetic factors can make one eventuality more likely than another, but at the end of the day it can be prevented. If one does not try a substance, one cannot become addicted to it. You still have a choice.